Howto16r1:Configure SIP over Websocket

Applies To

This information applies to

• innovaphone PBX
• Firmware 15r1sr15 [1510764], 16r1sr3 [1610936] and later.

More Information

Problem Details

RFC 7118 / SIP over Websocket (also referred to as "SIP-over-WS" or "SIP-over-WSS") is a transport method for the SIP protocol in which SIP messages are transmitted over a WebSocket connection instead of UDP or TCP. This is particularly relevant for WebRTC-based SIP clients (e.g. browser softphones), since browsers do not allow direct UDP/TCP socket connections for security reasons, but do support WebSocket connections.

The advantages of SIP over Websocket are:

• The connection uses standard web ports (80/443) and therefore generally passes through firewalls and proxies without issues.
• An encrypted connection (WSS = WebSocket Secure, analogous to HTTPS) can be used.
• Browser-based SIP/WebRTC clients can communicate directly with an innovaphone PBX without requiring additional plugins.

On an innovaphone PBX, the URL used by a SIP client to register via WebSocket is:

wss://<PBX-DNS-name or PBX-IP>/SIP/websocket

Example:

wss://pbx.example.com/SIP/websocket

System Requirements

• innovaphone PBX with at least Firmware 15r1sr15 [1510764] or 16r1sr3 [1610936]
• A valid certificate installed on the PBX for the WSS connection (since wss:// requires a TLS-encrypted connection)
• A SIP/WebRTC-capable client that supports SIP over Websocket (e.g. a browser softphone or corresponding app)

Installation and Configuration

To use SIP over Websocket on the innovaphone PBX:

1. Make sure a valid (ideally publicly trusted) TLS certificate is installed on the PBX.
2. If using a reverse proxy, the wss-path to the PBX must also be enabled
3. Configure the SIP client with the registrar/server address:

   wss://<PBX DNS name or IP>/SIP/websocket

4. Enter the username and password of the respective SIP object/user as usual for registration.