defaultSessionTimerEnable

Default Enable/Disable Session Expiration Services
          
Enables/Disables the session expiration services.
          
Disabling this service is not recommended since it will make
'dead' calls impossible to detect.
          
Questions and Answers:
          
Q - What is the session timer extension?
          
A - The session timer extension allows the detection of the
premature end of a call caused by a network problem or a
peer's failure.
          
The session timer mechanism sends a refresh request every n
seconds. This refresh request is either an reINVITE or an
UPDATE, according to configuration in the
SessionRefreshRequestMethod parameter. A sucessful response
(200 OK) to this refresh request means that the peer is still
alive and reachable. A timeout to this refresh request may
mean that there are problems in the signaling path, or that
the peer is simply not there anymore. In that case the call
will be shut down by using normal SIP means.
          
Q - SDP in Session Timer reINVITEs or UPDATEs:
          
A - If the reINVITE method is used, it is sent with the last
SDP that was negotiated. Reception of a session timer reINVITE
should not modify the connection characteristics. If the
UPDATE method is used, it is sent without any SDP offer.
          
Q - Relation between minimum and maximum values:
          
A - A UA that receives a Session-Expires header whose value is
smaller than the minimum it is willing to accept will reply a
422 Timer too low to the INVITE and terminate the call. The
phone will not ring.
          
It is up to the caller to decide what to do when it receives a
422 to its INVITE. The service will automatically retry the
INVITE, with a Session-Expires value equal to the minimum
value that the UAS was ready to accept (found in the Min-SE
header). This means that the maximum value as set in the
service might not be followed. This has the advantageous
effect of establishing the call even if the two endpoints have
conflicting values. The service will also keep retrying as
long as it gets 422 answers with different Min-SE values.
          
Q - Who refreshes?
          
A - Sending a session timer reINVITE or UPDATE is referred to
as refreshing the session. Normally, the UAS that receives the
INVITE will have the last word on who refreshes. The service
will always let the UAC (caller) do the refreshes if the
caller supports session timers. In the case the caller does
not support session timers, the service will assume the role
of the refresher.

MIB

MX-SIPEP-MIB

OID

.0.1400.1.600.100

Type

scalar

Access

readwrite

Status

current

Parent

sessionRefreshGroup

Siblings

3