[Serusers] IP Centrex features

Just found an IETF draft on how to implement PBX features in SIP http://www.voip-info.org/tiki-index.php?page=SIP+PBX+functions Maybe we can try to implement these in SER and document these functions on the Wiki? There's some of these in the source examples and in the howto's, but it might be good to document functions one by one. # Call Hold # Music on Hold # Unattended Transfer # Consultation Hold # Unconditional Call Forwarding # Attended Transfer # No Answer Call Forwarding # Busy Call Forwarding # Single-Line Extension # 3-way Call # Incoming Call Screening # Find-Me # Call Pickup # Call Park # Outgoing Call Screening # Automatic Redial Anyway, it's good reading material! /Olle