Does not perform ICE connectivity checks before ringing

[dpocock]

JsSIP is not sending back a 183 with ICE candidates in response to an INVITE.

It just sends back 180 and ringing starts.

It only does ICE checks after answering, this is not consistent with the ICE protocol.

Consequently, people sometimes experience missing audio/video streams. This should never happen.

The issue needs to be addressed with JsSIP rather than JSCommunicator.