Fedora Talk was based on Asterisk.
https://fedoraproject.org/wiki/Infrastructure/Asterisk
Asterisk has lots of great features (voicemail, queues, etc) but it is
mainly for voice, it emphasizes SIP and at the time it was also quite
bad with IPv6, TLS and NAT. FedRTC.org is based on a SIP proxy, not
Asterisk. SIP proxies (and XMPP servers) tend to have a much bigger
emphasis on connectivity and they also tend to have less features, so
they are easier to support. The repro SIP proxy has exceptionally good
TLS and IPv6 support. Asterisk is not really optimized for federation
but federation is quite easy with a SIP proxy because of the emphasis on
connectivity.
