In this section:
Use this screen to define retransmission and session keep-alive timer parameters
To View and Edit Timers
On the SBC main screen, go to Configuration > System Provisioning > Category: Trunk Provisioning > Trunk Group > SIP Trunk Group > Signaling > Timers.
The Edit Timers window is displayed. Figure 1: SIP Trunk Group - Signaling - Timers The following fields are displayed: Table 1: Sip Trunk Group - Signaling - Timers parameters Parameter Description T1 This is the SIP protocol retransmission timer T1 (in milliseconds). T1 is an estimate of the round-trip time (RTT). The value ranges from 1 to 10000 and the default value is 500. T2 Tcp Retransmit Timer Sctp Retransmit Timer The retransmit timer (in seconds) for SIP request over SCTP. The value ranges from 0 to 15 and the default value is 6. Session Keepalive The SIP protocol session keep-alive timer (in seconds). The value ranges from 0 to 65535 and the default value is 1800. Non Nat Keep Alive Timer Use this parameter to specify the keep-alive interval (in seconds) for a non-Nat'd device. The value ranges from 0 to 65535 and the default value is 60. Session Min SE Minimum expiration value (in seconds) accepted from a Session-Expires header. The value ranges from 0 to 65535 and the default value is 90. NOTE: When Session Min SE value is less than 90 seconds or when it equals 65535, the SBC does not send an INVITE upon receiving "422 Session Interval Too Small" error message. Session Termination Delta Time Enables a delay timer after switchover. The SBC continues retry with keepalive INVITE until the sipSwitchoverKeepAliveDelay timer is active. Timer range is 0-1024 seconds, default is 0. Make the required changes and click Save at the right hand bottom of the panel to save the changes made.
The Timers can be checked for each Address Context, for each Zone, for each SIP Trunk Group created or for all the Address Contexts, Zones and SIP Trunk Groups created. Use the drop-down box to select the desired Address Context, Zone and SIP Trunk Group.
This is the SIP protocol timer T2 (in milliseconds), and represents the maximum retransmit interval for non-INVITE requests and INVITE responses. The value ranges from 1 to 65535 and the default value is 4000. The retransmit timer (in seconds) for SIP request over TCP. The value ranges from 0 to 15 and the default value is 6. The time (in seconds) before session expiration at which the SBC sends a BYE if no session refresh request is received. This only applies when acting as the session keep-alive responder (i.e. not refresher) for a call. The value ranges from 0 to 65535 and the default value is 0. Ocs Dialog Timer This relay control block timer is restarted for each relay request received. If no request is received for the configured period, the dialog is deleted. When the timer is set to “0”, sessionKeepalive flag is disabled. The value ranges from 0 to 10080 and the default value is 1440. SIP Switchover Keep Alive Delay
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