[asterisk-dev] PJSIP_AOR and PJSIP_CONTACT Dialplan Functions

[Joshua Colp]

Currently within PJSIP there is no mechanism for the dialplan to examine 
things at an AOR or contact level. The depth to which you can venture is 
simply the endpoint.

In practice this can be annoying if you would like to examine things and 
change an outgoing INVITE (to add a header for auto answer, for 
example). To aid with this I'd like to propose two new dialplan 
functions: PJSIP_AOR and PJSIP_CONTACT.

The PJSIP_AOR dialplan function would take the name of an AOR and return 
the same information as "pjsip show aor". It would also make available a 
comma separated list of contacts currently bound to the AOR (be it 
externally added or configured).

Assumption:
An endpoint and AOR exist with the name "blink". A softphone is 
registered to the AOR.

Example:
${PJSIP_AOR(blink,mailboxes)} would return "1000" assuming it was 
configured with "1000".

Example:
${PJSIP_AOR(blink,contact)} would return 
"blink/sip:38725691 at 192.168.137.1:53015;transport=TCP"

The PJSIP_CONTACT dialplan function would take in the name of a contact 
as returned by PJSIP_AOR. It would make available the same information 
as "pjsip show contact" as well user agent if available.

Example:
${PJSIP_CONTACT(blink/sip:38725691 at 192.168.137.1:53015;transport=TCP,user_agent)} 
would return "Blink 0.9.1.2 (Windows)"

While both of these help to query for information if you follow the 
endpoint->aor->contact path there is currently no way, within a pre-dial 
handler, to know what contact (if any) is being used. I'd like to extend 
the ${CHANNEL()} implementation with two additional options, aor and 
contact, which would provide this information.

Assumption:
An outgoing channel using Dial(PJSIP/blink) is created.

Example:
${CHANNEL(aor)} would return "blink"

Example:
${CHANNEL(contact)} would return 
"blink/sip:38725691 at 192.168.137.1:53015;transport=TCP"

This assumes that the channel has been dialed using an AOR which 
resolved into a contact. If an explicit contact has been provided (which 
is done with PJSIP_DIAL_CONTACTS) then only contact would return a value.

This would allow the pre-dial handler to query for additional 
information about the contact being dialed in order to do things.

Thoughts?

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org