Only the most basic call processing for ring/busy/answer states of direct
targetted extensions is supported initially.  Distributed calling by multi-
registration on a single id is supported.

While call forwarding information is processed from config, and diversion
headers in invites are coded, it is not acted upon in any way.  In theory, we
will forward to registry entries, and other types of references to call groups
and/or external entries will be done by refer.

Subscriber module with actual registration to tethered service provider and
rewrite rules support to set "identity" in outgoing provider calls, and
rewrite callback for when authentication pushback happens

Hunt groups, Call Coverage and distribution models, day/night/state mode
processing.

actual sdp rewrite support in rtp proxying, only classification implemented

authentication handling for b2b outside dialing of arbitrary sip uri's.

Messaging and presense.

Routing and gateway operations including forced join on first ringer.

Ring mode for 183 ringback/preconnect.

Feature codes and dynamic setting of forwarding.

Message waiting notification.

More complete instant messaging support with offline queuing and offsite
destinations.

Routing plans and inter-node refers.

Smarter management of no answer processing.

Call hold and recall.

Call transfer/refer pass-thru on connected sessions.

Mysql db module plugin.

Packet forward plugin.

Radius auth plugin.

Stun plugin.

shell utility to server auth method.

shell utility to manage sipuser auth file.

