IP Office Technical Bulletin number 145
COMPAS ID 157236 Issue 2
Page 45 of 59
UPDATE without SDP for session refresh over SIP trunks
The addition of this new audit mechanism will validate that the connection is in place.
If not, the IP Office will free the trunk, thereby improving network resource utilization.
The IP Office can now negotiate RFC 4028 for session refresh over SIP Trunks. It
can either be the refresher or will expect UPDATE messages from remote party,
depending on negotiation. The session will be terminated if IP Office doesn’t receive
UPDATE/200 OK message for session refresh. In earlier IP Office releases, RE-
INVITE messages were used as the refresher. IP Office 8.1 is now RFC 4028
compliant. By default, UPDATE Supported is not enabled and IP Office will send RE-
INVITE messages for session refresh. If UPDATE Supported is Allow or Auto and the
other party supports UPDATE (specified in the “Allow” header), IP Office will send
UPDATE messages for session refresh.
From header shall be used by IP Office as calling identity whatever presence of
P-Asserted-Identity (PAI)
Although Service Providers typically use PAI for Caller ID delivery, there can be
situations where additional flexibility is required. IP Office provides an option to use
the ‘From’ Header. The administrator will have the option of selecting which Caller ID
information to use for displaying on the user equipment. By default, IP Office will
display PAI Caller ID present in the sip / tel uri consistent with pre-R8.1 behavior. If
the checkbox is set, the Caller ID present in ‘From’ sip uri will be used instead.