Business Server Integration

WeChat VoIP calling involves four parties: Mini Program, business server, Tange Cloud platform, and device. The business server is the custom core: it handles WeChat callbacks, calls Tange Cloud APIs, pushes messages to devices over a long-connection channel, and exposes APIs for both the Mini Program and devices.

Interface ownership:
WeChat provides: cgi-bin/token, sns/jscode2session, wxa/getsnticket, wxa/business/iot/voip/call server APIs, and iot_voip_notify callback push
Tange Cloud provides: POST /v1/token/wxvoip (TGV1-HMAC-SHA256 authentication)
Business server implements: all /v1/voip/* HTTP endpoints, the WeChat callback endpoint, and the device downlink channel

The API paths and field names in this document are reference examples. Use your own naming conventions in production — only the responsibilities need to match.

Read Call flows first.

I. What to Implement

In development order:

#	Module	Purpose
1	WeChat API wrapper	Encapsulate `access_token` retrieval and caching — all other WeChat APIs depend on it
2	WeChat callback handling	Receive `join_voip_room` → call Tange Cloud Token API → push downlink message to device
3	Device downlink channel	Server-to-device push channel for call notifications, cancel, and authorization updates
4	Mini Program APIs	WeChat login, VoIP authorization bind/unbind, SN Ticket issuance
5	Device APIs	Device media profile upload, authorized caller list, active call initiation
6	Call cancellation	Mini Program API + downlink `call_cancel`

II. WeChat API Wrapper

All WeChat APIs require access_token. Wrap this first.

2.1 access_token

GET https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid={appid}&secret={secret}

Valid for 7200s. Cache in memory with a 5-minute refresh margin.
Use per-appID mutex to avoid duplicate requests.

2.2 jscode2session

GET https://api.weixin.qq.com/sns/jscode2session?appid={appid}&secret={secret}&js_code={code}&grant_type=authorization_code

Mini Program calls wx.login() → code → server exchanges for openid.

2.3 getsnticket

POST https://api.weixin.qq.com/wxa/getsnticket?access_token={access_token}

json

{ "sn": "TIRZ00000001", "model_id": "HRHY_xxx" }

Returns sn_ticket for the Mini Program's wx.requestDeviceVoIP call.

2.4 iot/voip/call

POST https://api.weixin.qq.com/wxa/business/iot/voip/call?access_token={access_token}

json

{
  "model_id":  "HRHY_xxx",
  "sn":        "TIRZ00000001",
  "openid":    "o4DLd5...",
  "room_type": "voice",
  "version_type": 2,
  "payload":   ""
}

Calling this triggers an incoming call ring on the target user's Mini Program.

III. Handling WeChat Server Callbacks

This is the core processing chain. Prioritize this after obtaining access_token.

3.1 Endpoint

GET|POST /v1/voip/notification/:wx_app_id

Configure this URL in the WeChat Official Accounts admin panel:

https://your-domain.com/v1/voip/notification/{wx_app_id}

3.2 Processing Flow

POST /v1/voip/notification/:wx_app_id
  │
  ├─ ① Verify signature
  │     sha1(sort(token, timestamp, nonce)) == query param signature
  │     In secure mode (encrypt_type=aes), also verify msg_signature
  │
  ├─ ② AES decrypt (if encrypt_type=aes)
  │     EncodingAESKey (43-char Base64) → 32-byte key
  │     Decrypted format: random(16) + msg_len(4) + XML + app_id
  │     Verify trailing app_id matches config; reject otherwise
  │
  ├─ ③ Parse XML, only process:
  │     MsgType = "event"
  │     Event   = "iot_voip_notify"
  │     Action  = "join_voip_room"
  │     Return non-zero errcode for everything else
  │
  ├─ ④ Look up device media profile by Sn (uploaded via /v1/voip/device/profile)
  │     No profile → return errcode=10, cannot deliver call
  │
  ├─ ⑤ Call Tange Cloud POST /v1/token/wxvoip (see section IV)
  │     Input = WeChat callback fields (passthrough) + profile fields + server config
  │     Output = peer_id + token
  │
  ├─ ⑥ Push call_incoming to device via downlink channel (see section V)
  │
  └─ ⑦ Return {"errcode":0, "errmsg":"ok"} to WeChat

3.3 Field Flow Summary

"→ Token" means the field goes into the Tange Cloud Token request. "→ Downlink" means it goes into the call_incoming message.

Source	Field	→ Token	→ Downlink	Notes
WeChat XML	`Sn`	✓	—	Device ID, used for profile lookup
WeChat XML	`RoomId`	✓	✓	As `wx_room_id`
WeChat XML	`SessionKey`	✓	✓	As `wx_session_key`
WeChat XML	`ServerToken`	✓	✓	As `wx_server_token`
WeChat XML	`Payload`	✓	✓	Raw Base64 passthrough
WeChat URL	`openid`	—	✓	Caller identity
Device profile	All fields	✓	—	A/V parameters
Server config	`wx_app_id`	✓	✓
Server config	`wx_model_id`	✓	✓
Tange Cloud response	`peer_id`	—	✓	Device WHIP connect address
Tange Cloud response	`token`	—	✓	Device WHIP auth credential

Core principle: nearly all WeChat callback fields are passed through. The server does not interpret them — it only transports and assembles.

IV. Calling the Tange Cloud Token API

POST /v1/token/wxvoip — TGV1-HMAC-SHA256 authentication. See the API reference for complete field details and signing.

Called once per join_voip_room callback. Merges WeChat session fields with device capabilities to obtain the WHIP connection credentials the device needs.

Request body:

json

{
  "wx_session_key":      "<WeChat callback passthrough>",
  "wx_room_id":          "<WeChat callback passthrough>",
  "wx_session_token":    "<WeChat callback passthrough>",
  "wx_app_id":           "<Server config>",
  "device_id":           "<WeChat callback Sn>",
  "wx_payload":          "<WeChat callback Payload raw>",
  "wx_model_id":         "<Server config>",
  "calling_timeout_sec": "<Device profile>",
  "no_video":            "<Device profile>",
  "video_mt":            "<Device profile>",
  "screen_width":        "<Device profile>",
  "screen_height":       "<Device profile>",
  "audio_rate":          "<Device profile>",
  "audio_channels":      "<Device profile>"
}

Response:

json

{ "code": 0, "data": { "peer_id": "whips://wxvoip?...", "token": "v1.eyJ..." } }

Do not parse peer_id or token. Place them as-is into the downlink call_incoming.

V. Device Downlink Channel

The business server needs a long-connection channel to the device for pushing messages. The transport is up to you (MQTT, WebSocket, custom TCP, etc.). The only requirement: the server can address a specific device when it is online.

The following describes the message contract, independent of transport. For example with MQTT: the server connects to the broker as an MQTT client, sending commands to device/sn_{device_id}/cmd and notifications to device/sn_{device_id}/notify. The same pattern applies to WebSocket or custom TCP — only the routing mechanism differs.

5.1 Message Envelope

All downlink messages use the same JSON structure:

json

{ "type": "<message type>", "channel": "wx", "payload": { ... } }

5.2 Message Categories

Category	Description	Requires device ACK
Command (cmd)	Critical operations such as incoming call notifications	Yes
Notification (notify)	Informational messages such as cancel or authorization changes	No

How to distinguish the two categories depends on the transport. MQTT can use different topics (/cmd vs /notify); WebSocket can add a field like "category": "cmd".

5.3 call_incoming — Incoming Call Notification

Command-type message. Pushed after WeChat callback processing succeeds.

json

{
  "type": "call_incoming",
  "channel": "wx",
  "payload": {
    "peer_id":          "whips://wxvoip?...",
    "token":            "v1.eyJ...",
    "wx_app_id":        "wx27d4b2d7eb37eb58",
    "wx_model_id":      "HRHY_vJ9mHI2KQhd6yvj9Q",
    "wx_room_id":       "wxf830863...",
    "wx_user_openid":   "o4DLd5...",
    "wx_user_nickname": "",
    "wx_server_token":  "...",
    "wx_session_key":   "...",
    "wx_payload":       "...",
    "wx_call_id":       "...",
    "wx_from":          "..."
  }
}

Field sources:

Field	Source	Device usage
`peer_id`	Tange Cloud Token API response	First argument to `TiRtcWhipConnect`
`token`	Tange Cloud Token API response	Second argument to `TiRtcWhipConnect`
`wx_app_id`	Server config	Identifies the Mini Program
`wx_model_id`	Server config	IoT model ID
`wx_room_id`	WeChat callback `RoomId` (passthrough)	Needed for hangup/reject
`wx_user_openid`	WeChat callback URL query `openid` (passthrough)	Caller identity
`wx_server_token`	WeChat callback `ServerToken` (passthrough)	Pass to `TiRtcServiceRequest` on reject
`wx_session_key`	WeChat callback `SessionKey` (passthrough)	Session key
`wx_payload`	WeChat callback `Payload` (passthrough)	Custom data, Base64 raw
`wx_call_id`	Payload decoded `.id` (passthrough)	Call identifier
`wx_from`	Payload decoded `.from` (passthrough)	Caller side: `"miniapp"` or `"device"`

5.4 call_cancel — Cancel Call

Notification-type message.

json

{ "type": "call_cancel", "channel": "wx", "payload": { "wx_room_id": "wxf830863..." } }

Triggered when the Mini Program calls /v1/voip/user/cancel. The device matches wx_room_id against the current call and stops ringing or disconnects.

5.5 callers_update — Authorization Change

Notification-type message.

json

{ "type": "callers_update", "channel": "wx", "payload": {} }

Triggered when a user reports or deletes an authorization. The device should re-call GET /v1/voip/device/callers to refresh the local list.

VI. Mini Program–Facing APIs

Called by the Mini Program over HTTPS. Authentication is up to you.

POST /v1/voip/user/wechat-mini-login

json

// Request
{ "code": "wx_login_code" }
// Response
{ "code": 0, "data": { "wx_user_openid": "o4DLd5..." } }

Internally calls WeChat jscode2session.

6.2 VoIP Authorization Binding

POST /v1/voip/user/report-auth

Called after the Mini Program completes wx.requestDeviceVoIP.

json

// Request
{ "device_id": "TIRZ00000001", "wx_open_id": "o4DLd5...", "wx_model_id": "HRHY_xxx" }
// Response
{ "code": 0 }

After storing the authorization, push callers_update to the device via the downlink channel.

6.3 Delete Authorization

POST /v1/voip/user/delete-auth

json

// Request
{ "device_id": "TIRZ00000001", "wx_open_id": "o4DLd5..." }
// Response
{ "code": 0 }

6.4 SN Ticket

POST /v1/voip/user/sn-ticket

json

// Request
{ "device_id": "TIRZ00000001" }
// Response
{ "code": 0, "data": { "sn_ticket": "..." } }

Internally calls WeChat getsnticket.

6.5 Cancel Call

POST /v1/voip/user/cancel

json

// Request
{ "device_id": "TIRZ00000001", "wx_room_id": "wxf830863..." }
// Response
{ "code": 0 }

Pushes call_cancel to the device via the downlink channel. Only used when the Mini Program is the caller and the device has not yet answered.

VII. Device-Facing APIs

Called by the device over HTTPS. Authentication is up to you (e.g. JWT).

7.1 Upload Media Capabilities

POST /v1/voip/device/profile

Must be called on startup. Without it, the server cannot retrieve device capabilities when a WeChat callback arrives and the call notification will fail.

json

// Request
{
  "screen_width":        0,
  "screen_height":       0,
  "audio_rate":          8000,
  "audio_channels":      1,
  "video_mt":            "",
  "no_video":            true,
  "calling_timeout_sec": 30
}
// Response
{ "code": 0 }

These fields are assembled into the Tange Cloud Token request. Allowed values follow the Token API:

Profile field	Token field	Allowed values (see Server API)
`audio_rate`	`audio_rate`	`8000` / `16000`
`audio_channels`	`audio_channels`	`1` / `2`
`video_mt`	`video_mt`	`h264` / `mjpeg` / `none`
`no_video`	`no_video`	Set `true` for audio-only devices
`screen_width/height`	`screen_width` / `screen_height`	Required for non-audio-only
`calling_timeout_sec`	`calling_timeout_sec`	Ring timeout in seconds, default 30

For finer directional control, add optional fields: up_video_mt (h264/h265/mjpeg/none), down_video_mt (h264/mjpeg/none), down_audio_mt (alaw/amr/opus). Do not mix video_mt with up_video_mt/down_video_mt.

Call once per startup. The server overwrites on each update, then uses the stored values when assembling Token requests.

7.2 List Authorized Callers

GET /v1/voip/device/callers

json

// Response
{ "code": 0, "data": { "list": [
  { "wx_open_id": "o4DLd5...", "wx_app_id": "wx27d...", "wx_model_id": "HRHY...", "created_at": "..." }
] } }

The device selects a target user from this list before placing an active call.

7.3 Device Calls Mini Program

POST /v1/voip/device/call

json

// Request
{ "device_id": "TIRZ00000001", "wx_user_openid": "o4DLd5...", "wx_room_type": "voice" }
// Response
{ "code": 0 }

Internally calls WeChat iot/voip/call. After calling:

WeChat pushes an incoming call ring to the Mini Program
User answers → WeChat callbacks join_voip_room
Subsequent flow is identical to the Mini Program–initiated scenario

VIII. Differences Between the Two Scenarios

The only difference is who initiates the call.

Scenario 1: Mini Program Calls Device

Mini Program VoIP plugin ──▶ WeChat server ── join_voip_room ──▶ Business server
                                                                   │
                                                              ① Verify/decrypt
                                                              ② Look up profile
                                                              ③ Call Tange Token API
                                                              ④ Downlink call_incoming ──▶ Device
                                                                                           │
                                                                                      ⑤ TiRtcWhipConnect
                                                                                      ⑥ Receives cmdw=0x2000 (both sides established)

Server role: purely passive — receives WeChat callback, forwards to device.

Scenario 2: Device Calls Mini Program

Device ── POST /v1/voip/device/call ──▶ Business server ── WeChat iot/voip/call ──▶ WeChat server
                                                                                       │
                                                                                  Mini Program rings
                                                                                  User answers
                                                                                       │
                                        Business server ◀── join_voip_room ──── WeChat server
                                           │
                                      ① Verify/decrypt
                                      ② Look up profile
                                      ③ Call Tange Token API
                                      ④ Downlink call_incoming ──▶ Device
                                                                   │
                                                              ⑤ TiRtcWhipConnect
                                                              ⑥ Receives cmdw=0x2000 (both sides established)

Server role: first proactively calls WeChat API to initiate, then passively handles the callback — the callback processing logic is identical to Scenario 1.

Comparison

	Scenario 1 (Mini Program calls)	Scenario 2 (Device calls)
Call initiation	Mini Program VoIP plugin	Device calls `POST /v1/voip/device/call`
Extra server step	None	Call WeChat `iot/voip/call`
`join_voip_room` handling	Same	Same
Tange Token API	Same	Same
Downlink push	Same	Same
cmdw=0x2000	Received after WhipConnect, both sides established	Same

Business Server Integration ​

I. What to Implement ​

II. WeChat API Wrapper ​

2.1 access_token ​

2.2 jscode2session ​

2.3 getsnticket ​

2.4 iot/voip/call ​

III. Handling WeChat Server Callbacks ​

3.1 Endpoint ​

3.2 Processing Flow ​

3.3 Field Flow Summary ​

IV. Calling the Tange Cloud Token API ​

V. Device Downlink Channel ​

5.1 Message Envelope ​

5.2 Message Categories ​

5.3 call_incoming — Incoming Call Notification ​

5.4 call_cancel — Cancel Call ​

5.5 callers_update — Authorization Change ​

VI. Mini Program–Facing APIs ​

6.1 WeChat Login ​

6.2 VoIP Authorization Binding ​

6.3 Delete Authorization ​

6.4 SN Ticket ​

6.5 Cancel Call ​

VII. Device-Facing APIs ​

7.1 Upload Media Capabilities ​

7.2 List Authorized Callers ​

7.3 Device Calls Mini Program ​

VIII. Differences Between the Two Scenarios ​

Scenario 1: Mini Program Calls Device ​

Scenario 2: Device Calls Mini Program ​

Comparison ​

Business Server Integration

I. What to Implement

II. WeChat API Wrapper

2.1 access_token

2.2 jscode2session

2.3 getsnticket

2.4 iot/voip/call

III. Handling WeChat Server Callbacks

3.1 Endpoint

3.2 Processing Flow

3.3 Field Flow Summary

IV. Calling the Tange Cloud Token API

V. Device Downlink Channel

5.1 Message Envelope

5.2 Message Categories

5.3 call_incoming — Incoming Call Notification

5.4 call_cancel — Cancel Call

5.5 callers_update — Authorization Change

VI. Mini Program–Facing APIs

6.1 WeChat Login

6.2 VoIP Authorization Binding

6.3 Delete Authorization

6.4 SN Ticket

6.5 Cancel Call

VII. Device-Facing APIs

7.1 Upload Media Capabilities

7.2 List Authorized Callers

7.3 Device Calls Mini Program

VIII. Differences Between the Two Scenarios

Scenario 1: Mini Program Calls Device

Scenario 2: Device Calls Mini Program

Comparison