Describe the bug
Trying to alter the demo to talk to my Drachtio server which then proxies to a Cisco Meeting Server (a MCU that accepts SIP)

I get a Contact undefined error point to this file:

https://github.com/onsip/SIP.js/blob/master/src/core/dialogs/dialog.ts#L55

Logs

https://gist.github.com/philjones88/a8a865570de8f9f89679ace46261da02

192.168.4.31 = drachtio server
192.168.1.237 (philcms.vqlive.com) = cisco meeting server

The drachtio server is listening on 5060 + 5061 (tls) and for WS 5080 + 5081 (tls)

To Reproduce (if possible)
Steps to reproduce the behavior:

Pretty hard as you need a drachtio + cisco meeting server

Expected behavior

It to show remote video

Observed behavior

shows local video then errors with Contact undefined

Environment Information

• Drachtio
• Cisco Meeting Server
• Firefox

Additional context
Add any other context about the problem here.