To make and receive calls with a phone number, the app first registers this device with the operator network. It receives a registration ID, which it uses for both outgoing and incoming calls.
The app registers this device. The operator responds with a registration ID and expiration time.
The app renews registration before it expires. The operator responds with a new expiration time.
When calls are no longer needed, cancel registration to free up network resources.
Registration IDInclude it when making calls or subscribing to incoming call notifications.
Expiration timeSet by the operator; the app renews registration before it expires.
WebRTC Registration: How it works
- RegisterThe app submits deviceId (unchanged for the same device) and can specify a preferred expiration time.
- UseUse registrationId to create a call or subscribe to events such as incoming calls.
- Renew or cancelUse PUT to renew before expiration; use DELETE to cancel registration when it is no longer needed.
WebRTC Registration: API spec
POST /sessions to register; PUT /sessions/{registrationId} to renew; DELETE /sessions/{registrationId} to canceldeviceId (UUID generated by the app); optional registrationExpireTime for the preferred expiration time| Response fields | Meaning | Example |
|---|---|---|
| registrationId | Registration ID, used by both the call and event APIs | ln3C-ttOSk-ObcQ7A0-tYO1LXqy |
| regInfo.phoneNumber | Phone number used for this registration | +886912345678 |
| regInfo.regStatus | Registration status | Registered |
| expiresAt | Expiration time set by the operator | 2026-10-14T10:41:00Z |
Responses for three scenarios (excerpts)
ln3C-ttOSk-ObcQ7A0Registration IDRegisteredRegistration complete2026-10-14T10:41:00ZRegistration expiration timeln3C-ttOSk-ObcQ7A0Same registration ID2026-10-14T11:41:00ZNew expiry204Cancellation complete; no contentSpec source: CAMARA WebRTC r2.2 (WebRTC Registration Service v0.3.0)
WebRTC Registration: GSMA use cases
Enhanced call experiences
Problem to solveLets any connected device make calls over the operator network, with or without a SIM card.
WebRTC Registration's roleRegisters users’ devices to enable communication services.
Used together: WebRTC Call Handling, WebRTC Event Subscription
GSMA source ↗Sources: GSMA Open Gateway Use Case Library and API Descriptions (accessed 2026-10-14). Descriptions are summaries.