callSession.on(outboundMessage, callback)

Registers a callback function that will be invoked whenever a SIP message is sent from the client to the server.

The outboundMessage event allows developers to observe all outbound SIP traffic generated by the SDK. This includes SIP methods like INVITE, ACK, BYE, CANCEL, INFO, MESSAGE, and others sent during the lifecycle of a SIP session.

This event is primarily useful for debugging, logging, or implementing custom behavior based on outbound signaling.

Callback Parameters

Parameter	Description
message	An object representing the outbound SIP message.
message.method	The SIP method used (e.g., 'INVITE', 'BYE')
message.uri	The target URI of the message
message.headers	SIP headers
message.body	Optional SIP message body (e.g., SDP)

Usage Example

sipClient.on('outboundMessage', (message) => {
  console.log('Outbound SIP message:', message.method, message.uri);
  // Optionally inspect headers or modify logging
});

Notes

• This event provides visibility into low-level SIP operations but does not allow modification of the message before it is sent.

• When the SDK is initialized with debugging enabled, outbound messages may also be logged to the console automatically.