Transfer

This guide uses the full SIP.js API. The Simple User is intended to help get beginners up and running quickly. This guide is adopted from the SIP.js Github API documentation.

Make a Blind Transfer

In SIP to make a transfer you must send a REFER message to the endpoint that you have a session with. To do this in SIP.js you must call sesion.refer(target, options). The target can be either a valid URI or a SIP.js session. To make a blind transfer you should provide a SIP URI. We will use the UserAgent.makeUri() helper to make the URI of the transfer target.

const target = UserAgent.makeUri('sip:bob@example.com');
session.refer(target);

Make an Attended Transfer

The process to make an attended transfer is very similar to that of a Blind Transfer. Instead of providing a URI as the target you must provide a SIP.js session.

const replacementSession = newInviter(userAgent, UserAgent.makeURI("sip:bob@example.com"));
session.refer(replacementSession);

Handle an Incoming REFER

When an incoming REFER is received SIP.js by default will automatically follow it. If you would like more control over handling the incoming REFER you can create a callback function on the session delegate called onRefer(referral). This will get called with the referral when a REFER is received by SIP.js. If a callback is provided in the delegate SIP.js will no longer automaticall follow the REFER and the delegate is responsible for handling the message. If the referral is accepted, you will also need to write the code to follow it. There is a helper function on the referral called makeInviter() that can be used to make a new Inviter and follow the REFER.

const delegate = {
  onRefer: (referral) => {
    // Determine if you should accept or reject the referral
    if (shouldAcceptReferral(referral)) {
      referral.accept().then(() => {
        referral.makeInviter().invite();
      });
    } else {
      referral.reject();
    }
  }
}