Aastra Telecom 675xi Series - Manual (Page 19)

New Features in Release 2.4
RN-001029-03, Release 2.4, Rev 00 15
SIP IP Phone Models 9143i, 9480i, 9480i CT, and 675xi Series Phones Release Note 2.4
Reason Header Field in SIP Message
The IP Phones now support the receiving of the Reason Header Field in a SIP CANCEL message,
as described in RFC3326. This allows a call that is answered from somewhere else to still display
that it was answered elsewhere in the Callers List. Also, the missed calls indicator and counter do
not change.
Limitation
If the call is answered somewhere else, the duration of the call does not display in the Callers List.