2026-04-21 00:22:25 -04:00
8 changed files with 1081 additions and 8 deletions
@@ -4,6 +4,57 @@ All notable changes to seismo-relay are documented here.

 ---

+## v0.12.3 — 2026-04-20
+
+### Added
+
+- **Auto Call Home config protocol** — Full read/write/decode/encode pipeline for the
+  device's Remote Access → Setup Unit ACH settings, confirmed from 4-20-26 call home
+  settings captures.
+
+  **Protocol (new):**
+  - `SUB 0x2C` — Call Home Config READ (response `0xD3`); two-step read; data offset
+    `0x7C` = 124; raw payload 125 bytes (1-byte longer than DATA_LENGTH due to DLE-escaped
+    `\x10\x03` at raw[117:119] representing num_retries = 3)
+  - `SUB 0x7E` — Call Home Config WRITE (response `0x81`); 127-byte payload (125-byte read
+    payload + `\x00\x00`); offset = `data[1]+2 = 0x7E`; write format (DLE-aware checksum)
+  - `SUB 0x7F` — Call Home WRITE CONFIRM (response `0x80`); no data
+
+  **Field map (confirmed from 10-frame BW TX diff):**
+  - `raw[5]` — auto_call_home_enabled (bool)
+  - `raw[6:46]` — dial_string (40-byte null-padded ASCII)
+  - `raw[87]` — after_event_recorded (bool)
+  - `raw[91]` — at_specified_times (bool)
+  - `raw[93]` — time1_enabled / `raw[101]` — time1_hour / `raw[102]` — time1_min
+  - `raw[95]` — time2_enabled / `raw[105]` — time2_hour / `raw[106]` — time2_min
+  - `raw[117:119]` — `\x10\x03` (DLE-escaped 0x03 = num_retries value 3)
+  - `raw[120]` — time_between_retries_sec / `raw[122]` — wait_for_connection_sec / `raw[124]` — warm_up_time_sec
+
+  **Library (`minimateplus/`):**
+  - `models.py` — `CallHomeConfig` dataclass (14 fields; `raw` bytes preserved for
+    round-trip writes)
+  - `protocol.py` — `SUB_CALL_HOME = 0x2C`, `SUB_CALL_HOME_WRITE = 0x7E`,
+    `SUB_CALL_HOME_CONFIRM = 0x7F`; `read_call_home_config()`, `write_call_home_config()`
+  - `client.py` — `get_call_home_config()`, `set_call_home_config()`,
+    `_decode_call_home_config()` (handles DLE prefix at raw[117]),
+    `_encode_call_home_config()` (patches in-place; raises `ValueError` if hour/min = 3)
+
+  **REST API (`sfm/server.py`):**
+  - `GET /device/call_home` — reads and decodes call home config from device
+  - `POST /device/call_home` — reads, patches specified fields, writes back to device
+  - `CallHomeConfigBody` Pydantic model with 9 optional writable fields
+
+  **Web UI (`sfm/sfm_webapp.html`):**
+  - New "Call Home" tab with enable flag, dial string (read-only), after-event trigger,
+    at-specified-times flag, two time slots (enable + HH:MM each), and read-only retry
+    settings (num_retries, time_between_retries_sec, wait_for_connection_sec,
+    warm_up_time_sec)
+  - "Read from Device", "Write to Device", "Clear Form" action buttons
+  - Client-side guard: rejects hour or minute value equal to 3 with a clear message
+    explaining the DLE-encoding limitation
+
+---
+
 ## v0.12.2 — 2026-04-20

 ### Added / Fixed
@@ -2,7 +2,7 @@

 Ground-up Python replacement for **Blastware**, Instantel's Windows-only software for
 managing MiniMate Plus seismographs. Connects over direct RS-232 or cellular modem
-(Sierra Wireless RV50 / RV55). Current version: **v0.12.2**.
+(Sierra Wireless RV50 / RV55). Current version: **v0.12.3**.

 When new information about the protocol is discovered, please update the instantel_protocol_reference.md with the findings in addition to this document

@@ -27,9 +27,9 @@ CHANGELOG.md          ← version history

 ---

-## Current implementation state (v0.10.0)
+## Current implementation state (v0.12.3)

-Full read pipeline + write pipeline + erase pipeline + monitor log working end-to-end over TCP/cellular:
+Full read pipeline + write pipeline + erase pipeline + monitor log + call home config working end-to-end over TCP/cellular:

 | Step | SUB | Status |
 |---|---|---|
@@ -45,7 +45,8 @@ Full read pipeline + write pipeline + erase pipeline + monitor log working end-t
 | Event advance / next key | 1F | ✅ |
 | **Write commands (push config to device)** | **68–83** | ✅ new v0.8.0 |
 | **Erase all events** | **0xA3 → 0x1C → 0x06 → 0xA2** | ✅ new v0.9.0 |
-| **Monitor log entries (partial 0x2C records)** | **0A browse** | ✅ **new v0.10.0** |
+| **Monitor log entries (partial 0x2C records)** | **0A browse** | ✅ new v0.10.0 |
+| **Auto Call Home config (read + write)** | **2C → 7E → 7F** | ✅ **new v0.12.3** |

 `get_events()` sequence per event: `1E → 0A → 0C → 5A → 1F`

@@ -971,12 +972,104 @@ call-home.

 ---

+## Auto Call Home config (SUBs 0x2C / 0x7E / 0x7F) — confirmed 2026-04-20
+
+Full read/write pipeline confirmed from `bridges/captures/4-20-26/call home settings/`
+(10 BW TX write frames diffed against the S3 read response).
+
+Accessible in Blastware: **Remote Access → Setup Unit**.
+
+### Protocol
+
+**SUB 0x2C — Call Home Config READ (response 0xD3)**
+
+Standard two-step read: probe offset `0x0000`, data offset `0x007C` (124).
+Returns 125 raw bytes (one more than DATA_LENGTH) because the device encodes
+num_retries value `3` as `\x10\x03` on the wire — S3FrameParser preserves both
+bytes literally, shifting all subsequent field positions by +1.
+
+**SUB 0x7E — Call Home Config WRITE (response 0x81)**
+
+Write format (only BW_CMD `0x10` doubled on wire; DLE-aware checksum).
+Payload = 125-byte read payload + `\x00\x00` = 127 bytes.
+Offset = `data[1] + 2 = 0x7C + 2 = 0x7E`.
+
+**SUB 0x7F — Call Home WRITE CONFIRM (response 0x80)**
+
+Confirm frame, no data payload. Required after SUB 0x7E.
+
+### Field map (raw 125-byte array from `data_rsp.data[11:]`)
+
+| Raw Offset | Field | Notes |
+|---|---|---|
+| `[5]` | `auto_call_home_enabled` | `0x00`=off, `0x01`=on |
+| `[6:46]` | `dial_string` | 40-byte null-padded ASCII |
+| `[87]` | `after_event_recorded` | bool |
+| `[91]` | `at_specified_times` | bool |
+| `[93]` | `time1_enabled` | bool |
+| `[101]` | `time1_hour` | 0–23 |
+| `[102]` | `time1_min` | 0–59 |
+| `[95]` | `time2_enabled` | bool |
+| `[105]` | `time2_hour` | 0–23 |
+| `[106]` | `time2_min` | 0–59 |
+| `[117]` | DLE prefix `0x10` | Part of `\x10\x03` (DLE-escaped ETX encoding value 3) |
+| `[118]` | `num_retries` | Value = 3; detect via `raw[117] == 0x10` |
+| `[120]` | `time_between_retries_sec` | Shifted +1 from logical 119 |
+| `[122]` | `wait_for_connection_sec` | Shifted +1 from logical 121 |
+| `[124]` | `warm_up_time_sec` | Shifted +1 from logical 123 |
+
+**DLE-escaped 0x03 at raw[117:119]:** The byte value `0x03` is indistinguishable from the
+frame ETX terminator, so the device encodes it as `\x10\x03` (DLE + ETX inner-terminator).
+S3FrameParser in `STATE_AFTER_DLE` on ETX appends both bytes as literal payload. The write
+frame sends them verbatim — device accepts `\x10\x03` and interprets it as value 3.
+
+**Unconfirmed fields:** time slots 3 and 4 (offsets unknown), `modem_power_relay_enabled`.
+
+### `CallHomeConfig` model — models.py
+
+```python
+@dataclass
+class CallHomeConfig:
+    raw: Optional[bytes] = None                        # 125-byte raw read payload
+    auto_call_home_enabled: Optional[bool] = None      # raw[5]
+    dial_string: Optional[str] = None                  # raw[6:46]
+    after_event_recorded: Optional[bool] = None        # raw[87]
+    at_specified_times: Optional[bool] = None          # raw[91]
+    time1_enabled: Optional[bool] = None               # raw[93]
+    time1_hour: Optional[int] = None                   # raw[101]
+    time1_min: Optional[int] = None                    # raw[102]
+    time2_enabled: Optional[bool] = None               # raw[95]
+    time2_hour: Optional[int] = None                   # raw[105]
+    time2_min: Optional[int] = None                    # raw[106]
+    num_retries: Optional[int] = None                  # raw[118] (DLE-prefixed)
+    time_between_retries_sec: Optional[int] = None     # raw[120] (shifted +1)
+    wait_for_connection_sec: Optional[int] = None      # raw[122] (shifted +1)
+    warm_up_time_sec: Optional[int] = None             # raw[124] (shifted +1)
+```
+
+### SFM REST API — sfm/server.py
+
+```
+GET  /device/call_home?host=1.2.3.4&tcp_port=9034   ← read call home config
+POST /device/call_home?host=1.2.3.4&tcp_port=9034   ← write call home config
+```
+
+POST body fields (all optional): `auto_call_home_enabled`, `after_event_recorded`,
+`at_specified_times`, `time1_enabled`, `time1_hour`, `time1_min`, `time2_enabled`,
+`time2_hour`, `time2_min`.
+
+**Note:** `dial_string` is read-only in the current implementation (omitted from POST
+body) because writing a dial string may require DLE escaping for embedded control characters.
+
+---
+
 ## What's next

 - **Database** — SQLite store for events + monitor log entries; dedup by key; queryable
 - **Histograms** — decode histogram-mode A5 data (noise floor tracking)
 - Compliance config encoder — build raw write payloads from a `ComplianceConfig` object
 - Locate "Sensor Check" byte in compliance config (need capture with Disabled vs Before-monitoring)
+- Call Home — map time slots 3/4 offsets; add dial_string write support; confirm `modem_power_relay_enabled`
 - Modem manager — push RV50/RV55 configs via Sierra Wireless API
 - RV55 DCD/DTR issue — newer RV55 firmware doesn't assert DCD by default; units don't
  resume monitoring after call-home disconnect (`--restart-monitoring` flag deferred)
@@ -106,6 +106,7 @@
 | 2026-04-17 | §7.6.2, §14 | **RESOLVED — Float 6.206053 at channel_label+28 is the ADC-to-velocity scale factor.** Confirmed from Series III Interface Handbook §4.5 formula: `Range (×1) = 1.61133 V / Sensitivity (V/unit)`. For the standard Instantel geophone at Normal range (10.000 in/s): Sensitivity = 1.61133 / 10 = 0.161133 V/(in/s). The stored value is the **inverse sensitivity** = 1/0.161133 = **6.206053 (in/s)/V**. Cross-check: 1.61133 V × 6.206053 = 10.000 in/s ✅. The firmware uses it as: `PPV (in/s) = ADC_voltage (V) × 6.206053`. Value is identical on all Instantel standard geophones — it is a hardware/firmware constant, NOT a user-configurable setting. Do NOT write this field. Open question §14 item "Max Geo Range float 6.2061" is now **RESOLVED**. |
 | 2026-04-20 | §7.6.4 (NEW), §7.9, Appendix B | **CONFIRMED — Recording Mode byte location.** Three targeted captures (4-20-26) confirmed `recording_mode` at **`cfg[5]`** in the SUB 71 write payload (3-chunk compliance write). Method: single Blastware session, one initial E5 config pull, then three sequential "Send to unit" writes changing Recording Mode only. Diff of SUB 71 chunk-1 payloads: only `cfg[5]` and `cfg[1024]` changed; `cfg[1024]` delta exactly equals `cfg[5]` delta (chunk running checksum). In the E5 read response (sub-frame 1, page=0x0010), the field is at **`data[17]`** (= **anchor − 4** from the 10-byte anchor), one position earlier than in the write payload due to an extra `0x10` byte at `data[18]` present only in the read format. Enum: `0x00`=Single Shot, `0x01`=Continuous, `0x03`=Histogram, `0x04`=Histogram+Continuous. `0x02` value not yet observed. See §7.6.4 for full details. |
 | 2026-04-20 | §7.6.2, §7.9, Appendix B | **CONFIRMED — Geophone maximum range / sensitivity selector byte location.** Two targeted captures (4-20-26, geo sensitivity folder): one at Normal 10.000 in/s, one at Sensitive 1.250 in/s. E5 read payload diff: exactly 3 bytes differ at channel_label+33 for Tran/Vert/Long. Values: `0x00`=Normal 10.000 in/s, `0x01`=Sensitive 1.250 in/s. Same offset applies to the SUB 71 write payload (which is the same 2126-byte E5-format buffer round-tripped verbatim). **`channel_label+20` reads `0x01` in ALL captures regardless of range setting — it is NOT this field.** Previous hypothesis (uint8 at Tran+20, 0x01=Normal) was WRONG. Stored as `geo_range` in `ComplianceConfig`. Encoded to all three geo channel blocks (Tran/Vert/Long) at label+33. |
+| 2026-04-20 | §5.1, §5.3, §7.12 (NEW) | **NEW — Auto Call Home config protocol confirmed from 4-20-26 call home settings captures.** SUB 0x2C (Call Home Config READ, response 0xD3, data offset 0x7C=124) and SUB 0x7E/0x7F (WRITE + CONFIRM, response 0x81/0x80) confirmed. Write payload = read payload (125 bytes) + `\x00\x00` (127 bytes total). **DLE-escaped ETX at raw[117:119]:** the device returns logical value 0x03 (num_retries=3) as `\x10\x03` on the wire — S3FrameParser preserves both bytes as two literals, causing a +1 byte shift for all subsequent fields. Write frame sends these bytes verbatim (device interprets `\x10\x03` as literal value 3). Field map confirmed from 10-frame BW TX diff. See §7.12 for full layout. |

 ---

@@ -267,6 +268,7 @@ Step 4 — Device sends actual data payload:
 | `1C` | **MONITOR STATUS READ** | Two-step read, data offset 0x2C (44 bytes). `section[1] == 0x10` → monitoring; `0x00` → idle (CONFIRMED 2026-04-09, 100% accuracy on 144 frames). Payload length: 46–47 bytes IDLE, 48–49 bytes MONITORING. `frame.data` has checksum stripped — no trailing byte to skip. Battery/memory at end: `section[-10:-8]` = battery×100 (uint16 BE), `section[-8:-4]` = memory_total (uint32 BE), `section[-4:]` = memory_free (uint32 BE). | ✅ CONFIRMED 2026-04-09 |
 | `96` | **START MONITORING** | Single write frame, no data payload. Transitions unit from idle to monitoring mode (after optional on-device sensor check ~40 s). | ✅ CONFIRMED 2026-04-08 |
 | `97` | **STOP MONITORING** | Single write frame, no data payload. Stops monitoring, unit returns to idle. | ✅ CONFIRMED 2026-04-08 |
+| `2C` | **CALL HOME CONFIG READ** | Two-step read, data offset 0x7C (124 bytes + 1-byte DLE artefact = 125 raw bytes). Returns Auto Call Home configuration: enable flag, dial string, scheduled call times, retry settings, modem timing. Response SUB = 0xD3. **DLE note:** logical value 0x03 (num_retries) is returned as `\x10\x03` on the wire, which S3FrameParser preserves as two literal bytes — this shifts all subsequent field positions by +1. See §7.12 for full field map. | ✅ CONFIRMED 2026-04-20 |
 | `A3` | **ERASE ALL BEGIN** | Single frame, token=0xFE at params[7]. Initiates device memory erase. Must be followed by 0x1C probe+data + 0x06 probe+data + 0xA2 to complete. Standard `build_bw_frame` (not write-format). Response ack SUB = 0x5C. | ✅ CONFIRMED 2026-04-11 |
 | `A2` | **ERASE ALL CONFIRM** | Single frame, token=0xFE at params[7]. Commits the erase initiated by 0xA3. After this ack (SUB 0x5D), device memory is cleared and the event counter resets to `0x01110000`. | ✅ CONFIRMED 2026-04-11 |

@@ -296,6 +298,7 @@ All requests use CMD byte `0x02`. All responses use CMD byte `0x10 0x02` (which,
 | `98` | `67` | ✅ CONFIRMED 2026-04-08 |
 | `96` | `69` | ✅ CONFIRMED 2026-04-08 |
 | `97` | `68` | ✅ CONFIRMED 2026-04-08 |
+| `2C` | `D3` | ✅ CONFIRMED 2026-04-20 |
 | `A3` | `5C` | ✅ CONFIRMED 2026-04-11 |
 | `A2` | `5D` | ✅ CONFIRMED 2026-04-11 |

@@ -317,6 +320,8 @@ Write commands are initiated by Blastware (`BW->S3`) and use SUB bytes in the `0
 | `72` | **WRITE CONFIRM A** | Short frame, no data. Likely commit/confirm step after `71`. | `8D` | ✅ CONFIRMED |
 | `73` | **WRITE CONFIRM B** | Short frame, no data. | `8C` | ✅ CONFIRMED |
 | `74` | **WRITE CONFIRM C** | Short frame, no data. | `8B` | ✅ CONFIRMED |
+| `7E` | **CALL HOME CONFIG WRITE** | Writes Auto Call Home configuration (127 bytes: 125-byte read payload + `\x00\x00`). Offset = data[1]+2 = 0x7E. Write format (DLE-aware checksum, only BW_CMD `0x10` doubled on wire). Response SUB = 0x81. Must be followed by SUB 0x7F confirm. | `81` | ✅ CONFIRMED 2026-04-20 |
+| `7F` | **CALL HOME WRITE CONFIRM** | Short frame, no data. Commits call home config write from SUB 0x7E. Response SUB = 0x80. | `80` | ✅ CONFIRMED 2026-04-20 |
 | `82` | **TRIGGER CONFIG WRITE** | Writes trigger config block (0x1C bytes, mirrors SUB `1C` read). | `7D` | ✅ CONFIRMED |
 | `83` | **TRIGGER WRITE CONFIRM** | Short frame, no data. Likely commit step after `82`. | `7C` | ✅ CONFIRMED |

@@ -330,6 +335,8 @@ Write commands are initiated by Blastware (`BW->S3`) and use SUB bytes in the `0
 | `72` | `8D` |
 | `73` | `8C` |
 | `74` | `8B` |
+| `7E` | `81` |
+| `7F` | `80` |
 | `82` | `7D` |
 | `83` | `7C` |

@@ -1522,6 +1529,117 @@ and applies this heuristic on every call-home.

 ---

+### 7.12 Auto Call Home Config (SUB 0x2C / 0x7E / 0x7F) — ✅ CONFIRMED 2026-04-20
+
+> Confirmed from `bridges/captures/4-20-26/call home settings/` — 10 BW TX write frames
+> diffed against the S3 read payload. Accessible in Blastware via Remote Access → Setup Unit.
+
+#### 7.12.1 Read Protocol — SUB 0x2C → Response 0xD3
+
+Standard two-step read:
+
+| Step | Offset | Purpose |
+|---|---|---|
+| Probe | `0x0000` | Get ack (no data returned) |
+| Data | `0x007C` (124) | Receive 125-byte raw payload |
+
+`DATA_LENGTHS[SUB_CALL_HOME] = 0x7C`
+
+The raw payload is accessed as `data_rsp.data[11:]` — this is 125 bytes (not 124) because
+the device returns logical value 0x03 (num_retries=3) as the two-byte wire sequence
+`\x10\x03`. S3FrameParser is in `STATE_IN_FRAME` when it sees `0x10`, transitions to
+`STATE_AFTER_DLE`, and then on `0x03` (ETX qualifier) it would normally end the frame —
+but in the `_IN_FRAME_DLE` state it instead appends **both** the `0x10` and the `0x03`
+literally to the payload. The result: `raw[117] = 0x10`, `raw[118] = 0x03`, and all
+subsequent fields are shifted +1 from their logical positions.
+
+#### 7.12.2 Raw Payload Field Map (125 bytes, from `data_rsp.data[11:]`)
+
+> All offsets are into the 125-byte raw array. Offsets ≥ 119 are shifted +1 from logical
+> due to the DLE-escaped 0x03 at raw[117:119].
+
+| Raw Offset | Field | Type | Notes |
+|---|---|---|---|
+| `[5]` | `auto_call_home_enabled` | uint8 | `0x00` = disabled, `0x01` = enabled |
+| `[6:46]` | `dial_string` | ASCII | 40-byte null-padded, e.g. `"12345"` or phone number |
+| `[87]` | `after_event_recorded` | uint8 | `0x00` = off, `0x01` = on |
+| `[91]` | `at_specified_times` | uint8 | `0x00` = off, `0x01` = on |
+| `[93]` | `time1_enabled` | uint8 | `0x00` = off, `0x01` = on |
+| `[101]` | `time1_hour` | uint8 | 0–23 |
+| `[102]` | `time1_min` | uint8 | 0–59 |
+| `[95]` | `time2_enabled` | uint8 | `0x00` = off, `0x01` = on |
+| `[105]` | `time2_hour` | uint8 | 0–23 |
+| `[106]` | `time2_min` | uint8 | 0–59 |
+| `[117]` | DLE prefix `0x10` | — | Part of `\x10\x03` wire encoding for num_retries value 3 |
+| `[118]` | `num_retries` (value = 3) | uint8 | Logical value 0x03; check `raw[117] == 0x10` to detect DLE prefix |
+| `[120]` | `time_between_retries_sec` | uint8 | Shift +1 from logical 119 |
+| `[122]` | `wait_for_connection_sec` | uint8 | Shift +1 from logical 121 |
+| `[124]` | `warm_up_time_sec` | uint8 | Shift +1 from logical 123 |
+
+**Unconfirmed fields** (offsets not yet mapped from captures):
+- Time slots 3 and 4 (if they exist — Blastware UI only shows 2 time slots in observed sessions)
+- `modem_power_relay_enabled` (bool)
+- `storage_mode` (call home trigger on all events vs. triggered only?)
+
+#### 7.12.3 DLE-Escaped 0x03 — Critical Detail
+
+The `\x10\x03` sequence at raw[117:119] is **not** a DLE stuffing artifact in the usual
+sense. Standard DLE stuffing escapes `\x10` → `\x10\x10`. But here the device is encoding
+the integer value `3` in a position where the byte `\x03` would be indistinguishable from
+the frame ETX terminator. The device therefore sends `\x10\x03` (DLE + ETX = "inner-frame
+terminator" in S3 inner-frame syntax). S3FrameParser correctly handles this: in
+`STATE_AFTER_DLE`, seeing `\x03` (ETX) while **inside** an outer frame causes it to
+append both `\x10` and `\x03` as literal bytes rather than ending the frame. The outer
+frame only terminates on a **bare** `\x03` (without the DLE prefix).
+
+The write frame sends these bytes verbatim — the device accepts `\x10\x03` in the write
+payload and interprets it as the value 3. No transformation is needed in
+`_encode_call_home_config()`.
+
+**Limitation:** Any field that needs to encode the value `3` (0x03) requires this DLE
+prefix. The current encoder raises `ValueError` if any hour or minute field equals 3,
+since the encoder does not yet implement DLE-prefixed writes for arbitrary field positions.
+In practice, 3:00 AM / 3 minutes past are unlikely scheduled call times.
+
+#### 7.12.4 Write Protocol — SUB 0x7E → 0x7F
+
+Write format (same as other write commands — only BW_CMD `0x10` doubled on wire;
+all other bytes written raw; DLE-aware checksum):
+
+| Step | SUB | Payload | Offset | Response |
+|---|---|---|---|---|
+| Data write | `0x7E` | 127 bytes (125-byte read payload + `\x00\x00`) | `data[1]+2 = 0x7E` (126) | `0x81` |
+| Confirm | `0x7F` | empty | `0x00` | `0x80` |
+
+**Write payload construction:**
+```python
+write_payload = bytearray(raw_125_bytes)
+write_payload.append(0x00)
+write_payload.append(0x00)
+# patch fields in-place, then pass bytes(write_payload) to build_bw_write_frame
+```
+
+**Offset formula:**  `write_payload[1] = 0x7C` (same as DATA_LENGTH).
+`offset = write_payload[1] + 2 = 0x7C + 2 = 0x7E = 126`.
+This follows the identical pattern as SUB 0x68 (event index write) and SUB 0x69 (waveform write).
+
+**No preceding 0x2C read required** — Blastware sends SUB 0x7E directly using cached
+state. The `seismo-relay` implementation always reads first (`get_call_home_config()`)
+before writing for safety.
+
+#### 7.12.5 Implementation Notes
+
+- `MiniMateProtocol.read_call_home_config()` — standard two-step read; returns `data_rsp.data[11:]` (125 bytes raw)
+- `MiniMateProtocol.write_call_home_config(data)` — sends SUB 0x7E (127-byte payload) then SUB 0x7F confirm
+- `MiniMateClient.get_call_home_config()` → `CallHomeConfig` dataclass
+- `MiniMateClient.set_call_home_config(...)` — reads current config, patches via `_encode_call_home_config()`, writes back
+- `_decode_call_home_config(raw)` — handles DLE prefix detection at raw[117]
+- `_encode_call_home_config(raw, ...)` — patches in-place, appends 2 trailing zeros; raises `ValueError` if any hour/min == 3
+- REST API: `GET /device/call_home` and `POST /device/call_home` in `sfm/server.py`
+- Web UI: "Call Home" tab in `sfm/sfm_webapp.html`
+
+---
+
 ## 8. Timestamp Format

 Two timestamp wire formats are used:
@@ -35,6 +35,7 @@ from typing import Optional

 from .framing import S3Frame
 from .models import (
+    CallHomeConfig,
    ComplianceConfig,
    DeviceInfo,
    Event,
@@ -956,6 +957,93 @@ class MiniMateClient:
            notes=notes,
        )

+    # ── Call home config ──────────────────────────────────────────────────────
+
+    def get_call_home_config(self) -> CallHomeConfig:
+        """
+        Read the auto call home (ACH) configuration from the device.
+
+        Sends SUB 0x2C (two-step read) and decodes the raw 125-byte payload
+        into a CallHomeConfig object.
+
+        Returns:
+            CallHomeConfig with all confirmed fields populated.
+
+        Raises:
+            RuntimeError:  if not connected.
+            ProtocolError: on timeout or wrong response SUB.
+        """
+        proto = self._require_proto()
+        raw = proto.read_call_home_config()
+        return _decode_call_home_config(raw)
+
+    def set_call_home_config(
+        self,
+        *,
+        auto_call_home_enabled: Optional[bool]  = None,
+        after_event_recorded:   Optional[bool]  = None,
+        at_specified_times:     Optional[bool]  = None,
+        time1_enabled:          Optional[bool]  = None,
+        time1_hour:             Optional[int]   = None,
+        time1_min:              Optional[int]   = None,
+        time2_enabled:          Optional[bool]  = None,
+        time2_hour:             Optional[int]   = None,
+        time2_min:              Optional[int]   = None,
+    ) -> None:
+        """
+        Read the current call home config, apply any supplied changes, and
+        write the updated config back to the device.
+
+        Only non-None arguments are modified.  All other bytes are round-tripped
+        verbatim from the device.
+
+        Configurable fields
+        -------------------
+        auto_call_home_enabled : bool  — master enable for ACH
+        after_event_recorded   : bool  — call home after each triggered event
+        at_specified_times     : bool  — call home at scheduled times
+        time1_enabled          : bool  — enable time slot 1
+        time1_hour             : int   — hour for time slot 1 (0-23)
+        time1_min              : int   — minute for time slot 1 (0-59)
+        time2_enabled          : bool  — enable time slot 2
+        time2_hour             : int   — hour for time slot 2 (0-23)
+        time2_min              : int   — minute for time slot 2 (0-59)
+
+        Write sequence (confirmed from 4-20-26 call home settings captures):
+          SUB 0x2C (read, 2-step) → 125-byte raw payload
+          patch fields in-place
+          SUB 0x7E (write, 127-byte payload) → ack 0x81
+          SUB 0x7F (confirm) → ack 0x80
+
+        Raises:
+            RuntimeError:  if not connected.
+            ProtocolError: if any read or write step fails.
+        """
+        proto = self._require_proto()
+
+        # 1. Read current config
+        log.info("set_call_home_config: reading current config (SUB 0x2C)")
+        raw = proto.read_call_home_config()
+
+        # 2. Patch fields and build write payload
+        write_data = _encode_call_home_config(
+            raw,
+            auto_call_home_enabled=auto_call_home_enabled,
+            after_event_recorded=after_event_recorded,
+            at_specified_times=at_specified_times,
+            time1_enabled=time1_enabled,
+            time1_hour=time1_hour,
+            time1_min=time1_min,
+            time2_enabled=time2_enabled,
+            time2_hour=time2_hour,
+            time2_min=time2_min,
+        )
+
+        # 3. Write back
+        log.info("set_call_home_config: writing updated config (SUB 0x7E + 0x7F)")
+        proto.write_call_home_config(write_data)
+        log.info("set_call_home_config: complete")
+
    def poll(self) -> None:
        """
        Perform just the POLL startup handshake — no config reads.
@@ -2232,3 +2320,160 @@ def _decode_monitor_status(data: bytes) -> MonitorStatus:
        memory_total=memory_total,
        memory_free=memory_free,
    )
+
+
+def _decode_call_home_config(raw: bytes) -> CallHomeConfig:
+    """
+    Decode the raw 125-byte call home config payload into a CallHomeConfig.
+
+    *raw* is data[11:] from the SUB 0xD3 data response frame.
+
+    Field offsets (confirmed from 4-20-26 captures, all 11 BW+S3 pairs):
+      [5]       auto_call_home_enabled  (0x00=off, 0x01=on)
+      [6:46]    dial_string             40-byte null-padded ASCII
+      [87]      after_event_recorded    (0x01=on, 0x00=off)
+      [91]      at_specified_times      (0x01=on, 0x00=off)
+      [93]      time1_enabled           (0x01=on, 0x00=off)
+      [95]      time2_enabled           (0x01=on, 0x00=off)
+      [101]     time1_hour              uint8 decimal 0-23
+      [102]     time1_min               uint8 decimal 0-59
+      [105]     time2_hour              uint8 decimal 0-23
+      [106]     time2_min               uint8 decimal 0-59
+      [117:119] 10 03 = DLE-escaped num_retries=3  (logical value = 0x03)
+      [120]     time_between_retries_sec   (shifted +1 from logical by DLE prefix)
+      [122]     wait_for_connection_sec
+      [124]     warm_up_time_sec
+
+    The DLE-escaped ETX at raw[117:119] = b'\\x10\\x03' means the logical value
+    0x03 (3 retries) is stored there.  The S3FrameParser keeps both bytes verbatim.
+    Subsequent fields are at logical_offset + 1 in the raw byte array.
+    """
+    cfg = CallHomeConfig(raw=raw)
+
+    if len(raw) < 10:
+        return cfg
+
+    # Simple boolean and string fields — direct reads, no DLE complications
+    if len(raw) > 5:
+        cfg.auto_call_home_enabled = bool(raw[5])
+    if len(raw) >= 46:
+        ds = raw[6:46]
+        cfg.dial_string = ds.split(b"\x00", 1)[0].decode("ascii", errors="replace") or None
+    if len(raw) > 87:
+        cfg.after_event_recorded = bool(raw[87])
+    if len(raw) > 91:
+        cfg.at_specified_times = bool(raw[91])
+    if len(raw) > 93:
+        cfg.time1_enabled = bool(raw[93])
+    if len(raw) > 95:
+        cfg.time2_enabled = bool(raw[95])
+    if len(raw) > 102:
+        cfg.time1_hour = raw[101]
+        cfg.time1_min  = raw[102]
+    if len(raw) > 106:
+        cfg.time2_hour = raw[105]
+        cfg.time2_min  = raw[106]
+
+    # num_retries: raw[117]=0x10 (DLE prefix), raw[118]=0x03 (value)
+    # Subsequent fields shift by +1 from logical positions.
+    if len(raw) > 118 and raw[117] == 0x10:
+        cfg.num_retries = raw[118]            # 0x03 = 3
+        if len(raw) > 120:
+            cfg.time_between_retries_sec = raw[120]   # logical 119, shifted to 120
+        if len(raw) > 122:
+            cfg.wait_for_connection_sec = raw[122]    # logical 121, shifted to 122
+        if len(raw) > 124:
+            cfg.warm_up_time_sec = raw[124]           # logical 123, shifted to 124
+    elif len(raw) > 117:
+        # Fallback: no DLE prefix (num_retries is not 0x03)
+        cfg.num_retries = raw[117]
+        if len(raw) > 119:
+            cfg.time_between_retries_sec = raw[119]
+        if len(raw) > 121:
+            cfg.wait_for_connection_sec = raw[121]
+        if len(raw) > 123:
+            cfg.warm_up_time_sec = raw[123]
+
+    log.debug(
+        "_decode_call_home_config: enabled=%s dial=%r after_event=%s at_times=%s "
+        "t1=%s %02d:%02d  t2=%s %02d:%02d  retries=%s gap=%s wait=%s warmup=%s",
+        cfg.auto_call_home_enabled, cfg.dial_string,
+        cfg.after_event_recorded, cfg.at_specified_times,
+        cfg.time1_enabled, cfg.time1_hour or 0, cfg.time1_min or 0,
+        cfg.time2_enabled, cfg.time2_hour or 0, cfg.time2_min or 0,
+        cfg.num_retries, cfg.time_between_retries_sec,
+        cfg.wait_for_connection_sec, cfg.warm_up_time_sec,
+    )
+    return cfg
+
+
+def _encode_call_home_config(
+    raw: bytes,
+    *,
+    auto_call_home_enabled: Optional[bool]  = None,
+    after_event_recorded:   Optional[bool]  = None,
+    at_specified_times:     Optional[bool]  = None,
+    time1_enabled:          Optional[bool]  = None,
+    time1_hour:             Optional[int]   = None,
+    time1_min:              Optional[int]   = None,
+    time2_enabled:          Optional[bool]  = None,
+    time2_hour:             Optional[int]   = None,
+    time2_min:              Optional[int]   = None,
+) -> bytes:
+    """
+    Patch specific fields in the 125-byte raw call home payload and return
+    the 127-byte write payload (raw + b'\\x00\\x00' footer).
+
+    Only non-None arguments are modified.  All other bytes including the
+    DLE-escaped \\x10\\x03 at [117:119] are preserved verbatim for round-trip.
+
+    The write payload footer (2 trailing zeros) matches Blastware's confirmed
+    write frame format from the 4-20-26 captures.
+
+    CAUTION: hour and minute values must not equal 0x03 (3) — such values would
+    require DLE-escaping that this encoder does not implement.  Values 0x03 in
+    hour/minute slots are rejected with ValueError.
+    """
+    if len(raw) < 107:
+        raise ValueError(
+            f"call home raw payload too short: {len(raw)} bytes (need ≥107)"
+        )
+    buf = bytearray(raw)   # 125 bytes
+
+    def _set_bool(offset: int, value: Optional[bool]) -> None:
+        if value is not None:
+            buf[offset] = 0x01 if value else 0x00
+
+    def _set_uint8(offset: int, value: Optional[int], name: str) -> None:
+        if value is None:
+            return
+        if value == 0x03:
+            raise ValueError(
+                f"{name}={value} (0x03) requires DLE escaping — "
+                "not supported by this encoder; avoid using 3 for hour/minute fields"
+            )
+        buf[offset] = value & 0xFF
+
+    _set_bool(5,   auto_call_home_enabled)
+    _set_bool(87,  after_event_recorded)
+    _set_bool(91,  at_specified_times)
+    _set_bool(93,  time1_enabled)
+    _set_bool(95,  time2_enabled)
+    _set_uint8(101, time1_hour, "time1_hour")
+    _set_uint8(102, time1_min,  "time1_min")
+    _set_uint8(105, time2_hour, "time2_hour")
+    _set_uint8(106, time2_min,  "time2_min")
+    # num_retries, time_between_retries_sec, wait_for_connection_sec, warm_up_time_sec
+    # are not writable via this encoder — they're preserved verbatim including the
+    # DLE-escaped 0x03 at [117:119].
+
+    log.debug(
+        "_encode_call_home_config: patched fields: "
+        "enabled=%s after_event=%s at_times=%s "
+        "t1=%s %s:%s  t2=%s %s:%s",
+        auto_call_home_enabled, after_event_recorded, at_specified_times,
+        time1_enabled, time1_hour, time1_min,
+        time2_enabled, time2_hour, time2_min,
+    )
+
+    return bytes(buf) + b"\x00\x00"  # append 2-byte footer (confirmed BW pattern)
@@ -378,6 +378,78 @@ class ComplianceConfig:
    notes: Optional[str] = None            # extended notes / additional info


+# ── Call Home Config ──────────────────────────────────────────────────────────
+
+@dataclass
+class CallHomeConfig:
+    """
+    Auto Call Home (ACH) configuration from SUB 0x2C (response 0xD3).
+
+    Read with a standard two-step protocol (probe offset=0x00, data offset=0x7C).
+    Written via SUB 0x7E (write, 127-byte payload) + SUB 0x7F (confirm).
+
+    Confirmed from 4-20-26 call home settings captures (11 BW + S3 capture pairs).
+
+    Raw payload layout (data[11:] from S3 response, 125 bytes):
+      [0]     0x00           header byte
+      [1]     0x7C = 124     inner length (= offset for SUB 0x7E write - 2)
+      [2]     0xDC           constant
+      [3:5]   0x00 0x00      padding
+      [5]     auto_call_home_enabled  (0x00=off, 0x01=on) ✅
+      [6:46]  dial_string             40-byte null-padded ASCII ✅
+      [46:87] auto_answer_raw         AT command strings (not decoded) ✅ present
+      [87]    after_event_recorded    (0x01=on, 0x00=off) ✅
+      [91]    at_specified_times      (0x01=on, 0x00=off) ✅
+      [93]    time1_enabled           (0x01=on, 0x00=off) ✅
+      [95]    time2_enabled           (0x01=on, 0x00=off) ✅
+      [101]   time1_hour              uint8 decimal 0-23 ✅
+      [102]   time1_min               uint8 decimal 0-59 ✅
+      [105]   time2_hour              uint8 decimal 0-23 ✅
+      [106]   time2_min               uint8 decimal 0-59 ✅
+      [117]   DLE prefix (0x10)       ┐ DLE-escaped num_retries=3 (0x03)
+      [118]   0x03                    ┘ device stores/returns 0x03 DLE-escaped ✅
+      [120]   time_between_retries_sec uint8 (= 0x0F = 15 s default) ✅
+      [122]   wait_for_connection_sec  uint8 (= 0x3C = 60 s default) ✅
+      [124]   warm_up_time_sec         uint8 (= 0x3C = 60 s default) ✅
+
+    Write payload = raw 125 bytes + b'\\x00\\x00' (2 trailing zeros) = 127 bytes.
+    Offset for SUB 0x7E: data[1] + 2 = 0x7C + 2 = 0x7E = 126.
+
+    Note on DLE-escaped 0x03:  The device's S3 response DLE-escapes ETX (0x03)
+    bytes as \\x10\\x03.  The S3FrameParser preserves both bytes in frame.data.
+    Subsequent fields after offset 117 are therefore at raw_offset = logical+1.
+    The raw payload must be round-tripped verbatim in write; do NOT reapply DLE
+    destuffing or stripping.
+    """
+    raw: Optional[bytes] = None          # raw 125-byte read payload (for round-trip write)
+
+    # ── Main enable ──────────────────────────────────────────────────────────
+    auto_call_home_enabled: Optional[bool] = None    # raw[5] ✅
+
+    # ── Dial string ──────────────────────────────────────────────────────────
+    dial_string: Optional[str] = None                # raw[6:46] 40-byte null-padded ASCII ✅
+
+    # ── When to call ─────────────────────────────────────────────────────────
+    after_event_recorded: Optional[bool] = None      # raw[87] ✅
+    at_specified_times: Optional[bool] = None        # raw[91] ✅
+
+    # ── Time slot 1 ──────────────────────────────────────────────────────────
+    time1_enabled: Optional[bool] = None             # raw[93] ✅
+    time1_hour: Optional[int] = None                 # raw[101]  0-23 ✅
+    time1_min: Optional[int] = None                  # raw[102]  0-59 ✅
+
+    # ── Time slot 2 ──────────────────────────────────────────────────────────
+    time2_enabled: Optional[bool] = None             # raw[95] ✅
+    time2_hour: Optional[int] = None                 # raw[105]  0-23 ✅
+    time2_min: Optional[int] = None                  # raw[106]  0-59 ✅
+
+    # ── Retry / timeout settings (read-only; not writable via set_call_home_config) ──
+    num_retries: Optional[int] = None                # raw[117:119]=10 03 → value 3 ✅
+    time_between_retries_sec: Optional[int] = None   # raw[120] (shifted +1 by DLE) ✅
+    wait_for_connection_sec: Optional[int] = None    # raw[122] ✅
+    warm_up_time_sec: Optional[int] = None           # raw[124] ✅
+
+
 # ── Event ─────────────────────────────────────────────────────────────────────

@dataclass
@@ -65,6 +65,7 @@ SUB_WAVEFORM_HEADER  = 0x0A
 SUB_WAVEFORM_RECORD  = 0x0C
 SUB_BULK_WAVEFORM    = 0x5A
 SUB_COMPLIANCE       = 0x1A
+SUB_CALL_HOME        = 0x2C   # Call home config read  → response 0xD3 ✅
 SUB_UNKNOWN_2E       = 0x2E

 # Write command SUBs (= Read SUB + 0x60, confirmed from BW captures 3-11-26)
@@ -78,6 +79,10 @@ SUB_WRITE_CONFIRM_C      = 0x74   # Confirm C — sent after 69 ✅
 SUB_TRIGGER_CONFIG_WRITE = 0x82   # Write trigger config (0x22 + 0x60) ✅
 SUB_TRIGGER_CONFIRM      = 0x83   # Confirm trigger write ✅

+# Call home write SUBs (confirmed from 4-20-26 call home settings captures)
+SUB_CALL_HOME_WRITE      = 0x7E   # Write call home config  → response 0x81 ✅
+SUB_CALL_HOME_CONFIRM    = 0x7F   # Confirm call home write → response 0x80 ✅
+
 # Monitoring control SUBs (confirmed from 4-8-26/2ndtry BW TX capture)
 SUB_START_MONITORING     = 0x96   # Start monitoring  → response 0x69 ✅
 SUB_STOP_MONITORING      = 0x97   # Stop monitoring   → response 0x68 ✅
@@ -109,6 +114,7 @@ DATA_LENGTHS: dict[int, int] = {
    # SUB_WAVEFORM_HEADER (0x0A) is VARIABLE — length read from probe response
    # data[4].  Do NOT add it here; use read_waveform_header() instead. ✅
    SUB_WAVEFORM_RECORD: 0xD2,  # 210-byte waveform/histogram record ✅
+    SUB_CALL_HOME:      0x7C,   # 124-byte call home config ✅ (confirmed 4-20-26)
    SUB_UNKNOWN_2E:     0x1A,   # 26 bytes, purpose TBD 🔶
    0x09:               0xCA,   # 202 bytes, purpose TBD 🔶
    # SUB_COMPLIANCE (0x1A) uses a multi-step sequence with a 2090-byte total;
@@ -1087,6 +1093,89 @@ class MiniMateProtocol:
        self._send(frame)
        return self.recv_write_ack(expected_sub=rsp_sub)

+    # ── Call home config (SUBs 0x2C / 0x7E / 0x7F) ──────────────────────────
+
+    def read_call_home_config(self) -> bytes:
+        """
+        Read the auto call home configuration (SUB 0x2C → response 0xD3).
+
+        Standard two-step read: probe (offset=0x00) then data (offset=0x7C=124).
+        Returns the raw 125-byte payload (data[11:] of the data response).
+
+        Confirmed from 4-20-26 call home settings capture:
+          - Probe response: data[4]=0x7C (confirms data length = 124)
+          - Data response: 136 bytes total (11-byte echo header + 125 bytes payload)
+          - Payload[0:3] = 0x00 0x7C 0xDC (header: zero, inner-length, constant)
+          - Payload[5]  = auto_call_home_enabled
+          - Payload[6:46] = dial_string (40-byte null-padded ASCII "RADIO RING")
+
+        Returns:
+            Raw 125-byte call home config payload (data[11:]).
+            Suitable for round-trip write (append \\x00\\x00 → 127-byte write payload).
+
+        Raises:
+            ProtocolError: on timeout or wrong response SUB.
+        """
+        rsp_sub = _expected_rsp_sub(SUB_CALL_HOME)   # 0xFF - 0x2C = 0xD3
+        length  = DATA_LENGTHS[SUB_CALL_HOME]         # 0x7C = 124
+
+        log.debug("read_call_home_config: 0x2C probe")
+        self._send(build_bw_frame(SUB_CALL_HOME, 0))
+        self._recv_one(expected_sub=rsp_sub)
+
+        log.debug("read_call_home_config: 0x2C data request offset=0x%02X", length)
+        self._send(build_bw_frame(SUB_CALL_HOME, length))
+        data_rsp = self._recv_one(expected_sub=rsp_sub)
+
+        payload = data_rsp.data[11:]
+        log.debug("read_call_home_config: received %d payload bytes", len(payload))
+        return payload
+
+    def write_call_home_config(self, data: bytes) -> None:
+        """
+        Write the auto call home configuration (SUB 0x7E → 0x7F confirm).
+
+        Write sequence (confirmed from 4-20-26 call home settings captures):
+          SUB 0x7E  write 127-byte payload  → device acks SUB 0x81
+          SUB 0x7F  confirm (no data)       → device acks SUB 0x80
+
+        The 127-byte write payload = 125-byte read payload + b'\\x00\\x00'.
+        The offset field = data[1] + 2 = 0x7C + 2 = 0x7E = 126.
+
+        Write frame format: build_bw_write_frame (minimal DLE stuffing — only
+        BW_CMD is doubled; all other bytes are RAW).  The \\x10\\x03 sequence
+        within the payload is preserved as-is (device interprets DLE+ETX as the
+        literal value 0x03 per the inner-frame terminator convention).
+
+        Args:
+            data: 127-byte write payload (read payload + \\x00\\x00 footer).
+                  Must start with [0x00][0x7C][...] (standard header).
+
+        Raises:
+            ValueError:    if data is not exactly 127 bytes or lacks expected header.
+            ProtocolError: on timeout or wrong response SUB.
+        """
+        if len(data) < 2:
+            raise ValueError(f"call home write payload must be at least 2 bytes, got {len(data)}")
+        rsp_sub_write   = _expected_rsp_sub(SUB_CALL_HOME_WRITE)    # 0xFF - 0x7E = 0x81
+        rsp_sub_confirm = _expected_rsp_sub(SUB_CALL_HOME_CONFIRM)  # 0xFF - 0x7F = 0x80
+
+        # Offset formula: data[1] + 2 (same pattern as other single-chunk writes)
+        offset = data[1] + 2   # 0x7C + 2 = 0x7E = 126
+        frame = build_bw_write_frame(SUB_CALL_HOME_WRITE, data, offset=offset)
+        log.debug(
+            "write_call_home_config: %d bytes  data[1]=0x%02X  offset=0x%04X",
+            len(data), data[1], offset,
+        )
+        self._send(frame)
+        self.recv_write_ack(expected_sub=rsp_sub_write)
+        log.debug("write_call_home_config: write acked; sending confirm 0x7F")
+
+        confirm_frame = build_bw_write_frame(SUB_CALL_HOME_CONFIRM, b"")
+        self._send(confirm_frame)
+        self.recv_write_ack(expected_sub=rsp_sub_confirm)
+        log.debug("write_call_home_config: confirm acked — done")
+
    # ── Monitoring ────────────────────────────────────────────────────────────

    def read_monitor_status(self) -> S3Frame:
@@ -59,7 +59,7 @@ except ImportError:

 from minimateplus import MiniMateClient
 from minimateplus.protocol import ProtocolError
-from minimateplus.models import ComplianceConfig, DeviceInfo, Event, PeakValues, ProjectInfo, Timestamp
+from minimateplus.models import CallHomeConfig, ComplianceConfig, DeviceInfo, Event, PeakValues, ProjectInfo, Timestamp
 from minimateplus.transport import TcpTransport, DEFAULT_TCP_PORT
 from sfm.cache import SFMCache, get_cache
 from sfm.database import SeismoDb
@@ -302,6 +302,27 @@ def _serialise_compliance_config(cc: Optional["ComplianceConfig"]) -> Optional[d
    }


+def _serialise_call_home_config(ch: Optional["CallHomeConfig"]) -> Optional[dict]:
+    if ch is None:
+        return None
+    return {
+        "auto_call_home_enabled":    ch.auto_call_home_enabled,
+        "dial_string":               ch.dial_string,
+        "after_event_recorded":      ch.after_event_recorded,
+        "at_specified_times":        ch.at_specified_times,
+        "time1_enabled":             ch.time1_enabled,
+        "time1_hour":                ch.time1_hour,
+        "time1_min":                 ch.time1_min,
+        "time2_enabled":             ch.time2_enabled,
+        "time2_hour":                ch.time2_hour,
+        "time2_min":                 ch.time2_min,
+        "num_retries":               ch.num_retries,
+        "time_between_retries_sec":  ch.time_between_retries_sec,
+        "wait_for_connection_sec":   ch.wait_for_connection_sec,
+        "warm_up_time_sec":          ch.warm_up_time_sec,
+    }
+
+
 def _serialise_device_info(info: DeviceInfo) -> dict:
    return {
        "serial":             info.serial,
@@ -1075,6 +1096,144 @@ def device_monitor_stop(
    return {"status": "stopped"}


+# ── Call home config endpoints ───────────────────────────────────────────────
+
+
+@app.get("/device/call_home")
+def device_call_home_get(
+    port:     Optional[str] = Query(None,             description="Serial port (e.g. COM5)"),
+    baud:     int           = Query(38400,             description="Serial baud rate"),
+    host:     Optional[str] = Query(None,             description="TCP host — modem IP or ACH relay"),
+    tcp_port: int           = Query(DEFAULT_TCP_PORT, description=f"TCP port (default {DEFAULT_TCP_PORT})"),
+) -> dict:
+    """
+    Read the Auto Call Home (ACH) configuration from the device.
+
+    Sends SUB 0x2C (two-step read) and returns the decoded call home config.
+
+    Confirmed from 4-20-26 call home settings captures (BE11529).
+
+    Returns:
+        {
+          "auto_call_home_enabled": true/false,
+          "dial_string": "RADIO RING",
+          "after_event_recorded": true/false,
+          "at_specified_times": true/false,
+          "time1_enabled": true/false, "time1_hour": 19, "time1_min": 55,
+          "time2_enabled": false, "time2_hour": 0, "time2_min": 0,
+          "num_retries": 3,
+          "time_between_retries_sec": 15,
+          "wait_for_connection_sec": 60,
+          "warm_up_time_sec": 60
+        }
+    """
+    try:
+        def _do():
+            with _build_client(port, baud, host, tcp_port) as client:
+                client.poll()
+                return client.get_call_home_config()
+        ch_config = _run_with_retry(_do, is_tcp=_is_tcp(host))
+    except HTTPException:
+        raise
+    except ProtocolError as exc:
+        raise HTTPException(status_code=502, detail=f"Protocol error: {exc}") from exc
+    except OSError as exc:
+        raise HTTPException(status_code=502, detail=f"Connection error: {exc}") from exc
+    except Exception as exc:
+        raise HTTPException(status_code=500, detail=f"Device error: {exc}") from exc
+
+    return _serialise_call_home_config(ch_config) or {}
+
+
+class CallHomeConfigBody(BaseModel):
+    """
+    Request body for POST /device/call_home.
+
+    All fields are optional — only supplied (non-null) fields are modified.
+    All other call home config bytes are round-tripped verbatim from the device.
+
+    Confirmed writable fields (4-20-26 captures):
+      auto_call_home_enabled : bool  — master enable for auto call home
+      after_event_recorded   : bool  — call home after each triggered event
+      at_specified_times     : bool  — enable time-based scheduled calls
+      time1_enabled          : bool  — enable time slot 1
+      time1_hour             : int   — hour for slot 1 (0-23; avoid 3 — DLE escape limitation)
+      time1_min              : int   — minute for slot 1 (0-59; avoid 3)
+      time2_enabled          : bool  — enable time slot 2
+      time2_hour             : int   — hour for slot 2 (0-23; avoid 3)
+      time2_min              : int   — minute for slot 2 (0-59; avoid 3)
+
+    Read-only fields (not writable via this endpoint):
+      dial_string, num_retries, time_between_retries_sec,
+      wait_for_connection_sec, warm_up_time_sec
+    """
+    auto_call_home_enabled: Optional[bool]  = None
+    after_event_recorded:   Optional[bool]  = None
+    at_specified_times:     Optional[bool]  = None
+    time1_enabled:          Optional[bool]  = None
+    time1_hour:             Optional[int]   = None
+    time1_min:              Optional[int]   = None
+    time2_enabled:          Optional[bool]  = None
+    time2_hour:             Optional[int]   = None
+    time2_min:              Optional[int]   = None
+
+
+@app.post("/device/call_home")
+def device_call_home_set(
+    body:     CallHomeConfigBody,
+    port:     Optional[str] = Query(None,             description="Serial port (e.g. COM5)"),
+    baud:     int           = Query(38400,             description="Serial baud rate"),
+    host:     Optional[str] = Query(None,             description="TCP host — modem IP or ACH relay"),
+    tcp_port: int           = Query(DEFAULT_TCP_PORT, description=f"TCP port (default {DEFAULT_TCP_PORT})"),
+) -> dict:
+    """
+    Read the current call home config, apply supplied changes, and write back.
+
+    Only non-null fields are modified.  All other bytes round-trip verbatim.
+
+    Write sequence (confirmed from 4-20-26 call home settings captures):
+      SUB 0x2C (read 2-step) → 125-byte raw payload
+      patch fields
+      SUB 0x7E (write 127-byte payload) → ack 0x81
+      SUB 0x7F (confirm) → ack 0x80
+
+    Example body:
+        { "auto_call_home_enabled": true, "after_event_recorded": true,
+          "time1_enabled": true, "time1_hour": 20, "time1_min": 0 }
+    """
+    changed = body.model_dump(exclude_none=True)
+    log.info("POST /device/call_home  port=%s host=%s  fields=%s", port, host, list(changed.keys()))
+
+    try:
+        def _do():
+            with _build_client(port, baud, host, tcp_port) as client:
+                client.poll()
+                client.set_call_home_config(
+                    auto_call_home_enabled=body.auto_call_home_enabled,
+                    after_event_recorded=body.after_event_recorded,
+                    at_specified_times=body.at_specified_times,
+                    time1_enabled=body.time1_enabled,
+                    time1_hour=body.time1_hour,
+                    time1_min=body.time1_min,
+                    time2_enabled=body.time2_enabled,
+                    time2_hour=body.time2_hour,
+                    time2_min=body.time2_min,
+                )
+        _run_with_retry(_do, is_tcp=_is_tcp(host))
+    except HTTPException:
+        raise
+    except ProtocolError as exc:
+        raise HTTPException(status_code=502, detail=f"Protocol error: {exc}") from exc
+    except OSError as exc:
+        raise HTTPException(status_code=502, detail=f"Connection error: {exc}") from exc
+    except ValueError as exc:
+        raise HTTPException(status_code=422, detail=str(exc)) from exc
+    except Exception as exc:
+        raise HTTPException(status_code=500, detail=f"Device error: {exc}") from exc
+
+    return {"status": "ok", "updated_fields": changed}
+
+
 # ── Cache management endpoints ────────────────────────────────────────────────

@app.get("/cache/stats")
@@ -736,9 +736,10 @@

 <!-- ── Live tab bar ───────────────────────────────────────────────── -->
 <div class="tab-bar" id="live-tab-bar">
-  <button class="tab-btn active" data-tab="device"  onclick="switchTab('device')">Device</button>
-  <button class="tab-btn"        data-tab="events"  onclick="switchTab('events')">Events</button>
-  <button class="tab-btn"        data-tab="config"  onclick="switchTab('config')">Config</button>
+  <button class="tab-btn active" data-tab="device"    onclick="switchTab('device')">Device</button>
+  <button class="tab-btn"        data-tab="events"    onclick="switchTab('events')">Events</button>
+  <button class="tab-btn"        data-tab="config"    onclick="switchTab('config')">Config</button>
+  <button class="tab-btn"        data-tab="call-home" onclick="switchTab('call-home')">Call Home</button>
 </div>

 <!-- ════════════════════════════════════════════════════════════════
@@ -909,6 +910,123 @@

  </div><!-- end #tab-config -->

+<!-- ════════════════════════════════════════════════════════════════
+     TAB: Call Home
+═══════════════════════════════════════════════════════════════════ -->
+<div id="tab-call-home" class="tab-pane" style="display:none">
+
+  <div class="cfg-grid">
+
+    <!-- Enable / dial -->
+    <div class="cfg-section">
+      <div class="cfg-section-title">Auto Call Home</div>
+
+      <div class="cfg-field">
+        <label>Enable Auto Call Home</label>
+        <select id="ch-enabled">
+          <option value="">— unchanged —</option>
+          <option value="true">Enabled</option>
+          <option value="false">Disabled</option>
+        </select>
+      </div>
+
+      <div class="cfg-field">
+        <label>Dial String</label>
+        <input type="text" id="ch-dial-string" disabled placeholder="Read-only (e.g. RADIO RING)" />
+        <div class="hint">Read from device — not writable via this interface</div>
+      </div>
+
+      <div class="cfg-section-title" style="margin-top:16px">When to Call</div>
+
+      <div class="cfg-field">
+        <label>After Event Recorded</label>
+        <select id="ch-after-event">
+          <option value="">— unchanged —</option>
+          <option value="true">Yes</option>
+          <option value="false">No</option>
+        </select>
+      </div>
+
+      <div class="cfg-field">
+        <label>At Specified Times</label>
+        <select id="ch-at-times">
+          <option value="">— unchanged —</option>
+          <option value="true">Yes</option>
+          <option value="false">No</option>
+        </select>
+      </div>
+
+    </div>
+
+    <!-- Scheduled call times -->
+    <div class="cfg-section">
+      <div class="cfg-section-title">Scheduled Call Times</div>
+
+      <div class="cfg-field">
+        <label>Time Slot 1</label>
+        <div style="display:flex;gap:8px;align-items:center">
+          <select id="ch-t1-enabled" style="width:120px">
+            <option value="">— enable —</option>
+            <option value="true">Enabled</option>
+            <option value="false">Disabled</option>
+          </select>
+          <input type="number" id="ch-t1-hour" min="0" max="23" step="1" placeholder="HH" style="width:64px" />
+          <span>:</span>
+          <input type="number" id="ch-t1-min"  min="0" max="59" step="1" placeholder="MM" style="width:64px" />
+        </div>
+        <div class="hint">Hour (0-23) and minute (0-59).  Avoid value 3 (DLE limitation).</div>
+      </div>
+
+      <div class="cfg-field">
+        <label>Time Slot 2</label>
+        <div style="display:flex;gap:8px;align-items:center">
+          <select id="ch-t2-enabled" style="width:120px">
+            <option value="">— enable —</option>
+            <option value="true">Enabled</option>
+            <option value="false">Disabled</option>
+          </select>
+          <input type="number" id="ch-t2-hour" min="0" max="23" step="1" placeholder="HH" style="width:64px" />
+          <span>:</span>
+          <input type="number" id="ch-t2-min"  min="0" max="59" step="1" placeholder="MM" style="width:64px" />
+        </div>
+        <div class="hint">Hour (0-23) and minute (0-59).  Avoid value 3 (DLE limitation).</div>
+      </div>
+
+      <div class="cfg-section-title" style="margin-top:16px">Retry Settings (read-only)</div>
+
+      <div class="cfg-field">
+        <label>Number of Retries</label>
+        <input type="text" id="ch-num-retries" disabled placeholder="—" />
+      </div>
+
+      <div class="cfg-field">
+        <label>Time Between Retries (s)</label>
+        <input type="text" id="ch-retry-gap" disabled placeholder="—" />
+      </div>
+
+      <div class="cfg-field">
+        <label>Wait for Connection (s)</label>
+        <input type="text" id="ch-wait-conn" disabled placeholder="—" />
+      </div>
+
+      <div class="cfg-field">
+        <label>Warm-up Time (s)</label>
+        <input type="text" id="ch-warmup" disabled placeholder="—" />
+      </div>
+
+    </div>
+
+  </div>
+
+  <div class="cfg-actions">
+    <button class="btn btn-ghost" id="ch-read-btn" onclick="readCallHome()" disabled>Read from Device</button>
+    <button class="btn btn-success" id="ch-write-btn" onclick="writeCallHome()" disabled>Write to Device</button>
+    <button class="btn btn-ghost" onclick="clearCallHomeForm()">Clear Form</button>
+    <span id="ch-status"></span>
+  </div>
+
+</div><!-- end #tab-call-home -->
+
 </div><!-- end #section-live -->

 <!-- ════════════════════════════════════════════════════════════════
@@ -1494,6 +1612,134 @@ async function writeConfig() {
  }
 }

+// ── Call Home form ─────────────────────────────────────────────────────────────
+function setChStatus(msg, type) {
+  const el = document.getElementById('ch-status');
+  el.textContent = msg;
+  el.style.color = type === 'ok' ? '#4caf50' : type === 'error' ? '#f44336' : '#aaa';
+}
+
+function populateCallHomeForm(ch) {
+  if (!ch) return;
+  const qs2 = id => document.getElementById(id);
+
+  // Read-only display fields
+  if (ch.dial_string != null)          qs2('ch-dial-string').value = ch.dial_string || '';
+  if (ch.num_retries != null)          qs2('ch-num-retries').value = ch.num_retries;
+  if (ch.time_between_retries_sec != null) qs2('ch-retry-gap').value = ch.time_between_retries_sec;
+  if (ch.wait_for_connection_sec != null)  qs2('ch-wait-conn').value = ch.wait_for_connection_sec;
+  if (ch.warm_up_time_sec != null)     qs2('ch-warmup').value = ch.warm_up_time_sec;
+
+  // Editable select/input fields (use "" for "unchanged" state when value is null)
+  function setBool(id, val) {
+    if (val != null) document.getElementById(id).value = val ? 'true' : 'false';
+  }
+  setBool('ch-enabled',    ch.auto_call_home_enabled);
+  setBool('ch-after-event', ch.after_event_recorded);
+  setBool('ch-at-times',    ch.at_specified_times);
+  setBool('ch-t1-enabled',  ch.time1_enabled);
+  setBool('ch-t2-enabled',  ch.time2_enabled);
+  if (ch.time1_hour != null) qs2('ch-t1-hour').value = ch.time1_hour;
+  if (ch.time1_min  != null) qs2('ch-t1-min').value  = ch.time1_min;
+  if (ch.time2_hour != null) qs2('ch-t2-hour').value = ch.time2_hour;
+  if (ch.time2_min  != null) qs2('ch-t2-min').value  = ch.time2_min;
+}
+
+function clearCallHomeForm() {
+  ['ch-enabled','ch-after-event','ch-at-times','ch-t1-enabled','ch-t2-enabled']
+    .forEach(id => { document.getElementById(id).selectedIndex = 0; });
+  ['ch-t1-hour','ch-t1-min','ch-t2-hour','ch-t2-min']
+    .forEach(id => { document.getElementById(id).value = ''; });
+  // Keep read-only display fields but clear them too
+  ['ch-dial-string','ch-num-retries','ch-retry-gap','ch-wait-conn','ch-warmup']
+    .forEach(id => { document.getElementById(id).value = ''; });
+  setChStatus('');
+}
+
+async function readCallHome() {
+  if (!devHost()) { setChStatus('Not connected.', 'error'); return; }
+  setChStatus('Reading call home config from device…');
+  document.getElementById('ch-read-btn').disabled = true;
+  try {
+    const r = await fetch(`${api()}/device/call_home?${deviceParams()}`);
+    if (!r.ok) { const e = await r.json().catch(()=>({})); throw new Error(e.detail || r.statusText); }
+    const ch = await r.json();
+    populateCallHomeForm(ch);
+    setChStatus('Call home config loaded from device.', 'ok');
+  } catch(e) {
+    setChStatus(`Read failed: ${e.message}`, 'error');
+  } finally {
+    document.getElementById('ch-read-btn').disabled = false;
+  }
+}
+
+async function writeCallHome() {
+  if (!devHost()) { setChStatus('Not connected.', 'error'); return; }
+
+  // Build body — only include fields that have values
+  const body = {};
+
+  function getBool(id) {
+    const v = document.getElementById(id).value;
+    return v === '' ? null : v === 'true';
+  }
+  function getIntField(id) {
+    const v = document.getElementById(id).value.trim();
+    return v === '' ? null : parseInt(v, 10);
+  }
+
+  const en = getBool('ch-enabled');
+  if (en !== null) body.auto_call_home_enabled = en;
+  const ae = getBool('ch-after-event');
+  if (ae !== null) body.after_event_recorded = ae;
+  const at = getBool('ch-at-times');
+  if (at !== null) body.at_specified_times = at;
+  const t1e = getBool('ch-t1-enabled');
+  if (t1e !== null) body.time1_enabled = t1e;
+  const t1h = getIntField('ch-t1-hour');
+  if (t1h !== null) body.time1_hour = t1h;
+  const t1m = getIntField('ch-t1-min');
+  if (t1m !== null) body.time1_min = t1m;
+  const t2e = getBool('ch-t2-enabled');
+  if (t2e !== null) body.time2_enabled = t2e;
+  const t2h = getIntField('ch-t2-hour');
+  if (t2h !== null) body.time2_hour = t2h;
+  const t2m = getIntField('ch-t2-min');
+  if (t2m !== null) body.time2_min = t2m;
+
+  if (Object.keys(body).length === 0) {
+    setChStatus('No fields to write — change at least one field.', 'error');
+    return;
+  }
+
+  // Warn about value 3 in hour/min fields
+  const hourMinFields = [body.time1_hour, body.time1_min, body.time2_hour, body.time2_min];
+  if (hourMinFields.some(v => v === 3)) {
+    setChStatus('Error: value 3 in hour/minute fields is not supported (DLE protocol limitation).', 'error');
+    return;
+  }
+
+  const fieldsStr = Object.keys(body).join(', ');
+  setChStatus(`Writing ${Object.keys(body).length} field(s)…`);
+  document.getElementById('ch-write-btn').disabled = true;
+
+  try {
+    const r = await fetch(`${api()}/device/call_home?${deviceParams()}`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(body),
+    });
+    if (!r.ok) { const e = await r.json().catch(()=>({})); throw new Error(e.detail || r.statusText); }
+    setChStatus(`Written: ${fieldsStr}`, 'ok');
+    // Re-read to confirm changes
+    await readCallHome();
+  } catch(e) {
+    setChStatus(`Write failed: ${e.message}`, 'error');
+  } finally {
+    document.getElementById('ch-write-btn').disabled = false;
+  }
+}
+
 // ── Events ─────────────────────────────────────────────────────────────────────
 function populateEventChips() {
  const el = document.getElementById('event-chips');