Early-Only" Parameter In Replaces Header Rfc3891; Reason Header Field In Sip Message; Configurable "Allow" And "Allow-Event" Optional Headers - Aastra 9143i Series Administrator's Manual

IP Phone Administrator Guide
Advanced Operational Features

"Early-Only" Parameter in Replaces Header RFC3891

The phones support the "early-only" parameter in the "Replaces" header
according to RFC3891. When the phone receives a Replaces header with the
early-only parameter, it replaces the existing dialog if the call is still in the early
state. If the call has been answered, then the Replaces request is rejected.

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.
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Note: This feature is not supported in outgoing requests.
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