AASTRA 6700i series, 9143, 9480i, 9480i CT SIP Administrator Guide EN - Manual (Page 675)

6-48 41-001343-01 Rev 03, Release 3.2.2
Reason Header Field in SIP Message
The IP Phones 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
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.
Configurable “Allow” and “Allow-Event” Optional Headers
On the IP Phones, an Administrator can enable or disable whether or not the optional “Allow”
and “Allow-Events” headers are included in the NOTIFY message from the phone.
SIP NOTIFY messages from the phone may contain optional headers called “Allow” and
“Allow-events”. If the NOTIFY message contains these headers, the UDP packet returned by the
server may be too large and may fragment the packet. To prevent the fragmenting of the UDP
packet, the “Allow” and “Allow-events” headers may be removed using the parameter, “sip
notify opt headers ”. If this parameter is set to “0” (disabled), the optional headers are not
included in the SIP NOTIFY neassage which reduces the size of the packet returned by the
server, and prevents fragmentation of the packet.
The value set for this parameter specifies whether or not to include the optional headers in the
SIP NOTIFY message from the phone.
An Administrator can enable/disable the optional “Allow” and “Allow-Event” headers using the
following parameter in the configuration files:
•
sip notify opt headers
Enablling/Disabling Optional “Allow” and “Allow-Event” Headers
Use the following procedure to enable/disable “Allow” and “Allow-Event” headers.
Configuration Files
For the specific parameter you can set in the configuration files, see Appendix A, the section, “Optional
“Allow” and “Allow-Event” Headers” on page A-247.