Hello,

Does anyone know whether pbxnsip uses RFC 3856 to know the state of phones which are connected to it or does it use some other way to know phone presence?

Thanks
Kevin

The PBX is at this point just a presence agent that receives the presence information from a user-agent and then notifies it to subscribed parties. It does not look at the presence document itself.

A UA that wants to publish its presence state must use PUBLISH and the event must be set to "presence". Pretty SIMPLE!

Thanks! One more question if I may:

When pbxnsip is attempting to identify inbound calls, which SIP headers does it use and which part of those headers? I would imagine that the 'FROM' header is used, but what about 'remote-party-id' headers? What does it do with the calling party name part of the FROM header? Also, must the extension it identifies be currently REGISTERed or is it sufficient for it to exist in the DB?

Kevin

The PBX uses the "From" header for Caller-ID information. For authentication, if present, the "P-Preferred-Identity" header is used - if present. IMHO this is pretty much compliant to RFC3325. "Remote-Party-ID" is practically a Cisco-proprietary header; the IETF draft expired many years ago and this is good - as this header screws up the meaning of the From header and makes it difficult to keep track of network identity and display identity. RFC3325 replaced the draft later.

For authentication purposes you don't have to be registered. If you are on a IP address that is routable from the PBX that's fine. However, if the SBC has to take care about the device it should be registered. Especially considering newer stuff like outbound, the registration plays a major role in dealing with devices that are behind firewalls and NAT.