Cisco Cisco IOS Software Release 12.2(8)T
SIP Media Inactivity Timer
Configuration Tasks
4
Cisco IOS Release 12.2(8)T and 12.2(11)T
Configuring the SIP Media Inactivity Timer
The SIP Media Inactivity Timer feature requires the configuration of the ip rtcp report interval
command and the timer receive-rtcp command to enable detection of RTCP packets by the gateway.
When these commands are configured, the gateway uses RTCP report detection, rather than Real-Time
Protocol (RTP) packet detection, to determine whether calls on the gateway are still active or should be
disconnected. This method is more reliable because there are periods during voice calls when one or both
parties are not sending RTP packets.
command and the timer receive-rtcp command to enable detection of RTCP packets by the gateway.
When these commands are configured, the gateway uses RTCP report detection, rather than Real-Time
Protocol (RTP) packet detection, to determine whether calls on the gateway are still active or should be
disconnected. This method is more reliable because there are periods during voice calls when one or both
parties are not sending RTP packets.
One common example of a voice session in which no RTP is sent is when a caller dials into a conference
call and mutes his endpoint. If voice activity detection (VAD, also known as silence suppression) is
enabled, no RTP packets are sent while the endpoint is muted. However, the muted endpoint continues
to send RTCP reports at the interval specified by the ip rtcp report interval command.
call and mutes his endpoint. If voice activity detection (VAD, also known as silence suppression) is
enabled, no RTP packets are sent while the endpoint is muted. However, the muted endpoint continues
to send RTCP reports at the interval specified by the ip rtcp report interval command.
The timer receive-rtcp value argument (or Mfactor) is multiplied with the interval that is set using the
ip rtcp report interval command. If no RTCP packets are received in the resulting time period, the call
is disconnected. The gateway signals the disconnect to the SIP network and the TDM network so that
upstream and downstream devices can clear their resources. The gateway sends a SIP BYE to disconnect
the call and sends a Q.931 DISCONNECT back to the TDM network to clear the call upon the expiration
of the timer. The Q.931 DISCONNECT is sent with a Cause code value of 3 (no route). There is no Q.931
Progress Indicator (PI) value included in the DISCONNECT.
ip rtcp report interval command. If no RTCP packets are received in the resulting time period, the call
is disconnected. The gateway signals the disconnect to the SIP network and the TDM network so that
upstream and downstream devices can clear their resources. The gateway sends a SIP BYE to disconnect
the call and sends a Q.931 DISCONNECT back to the TDM network to clear the call upon the expiration
of the timer. The Q.931 DISCONNECT is sent with a Cause code value of 3 (no route). There is no Q.931
Progress Indicator (PI) value included in the DISCONNECT.
To configure the SIP Media Inactivity Timer feature, enter the following commands beginning in global
configuration mode:
configuration mode:
Note
RFC 1889,
, recommends a minimum 5-second
average reporting interval between successive RTCP reports. It also recommends that this interval be
varied randomly. The randomization function is performed automatically and cannot be disabled.
Therefore, the reporting interval does not remain constant throughout a given voice session, but its
average is the specified reporting interval.
varied randomly. The randomization function is performed automatically and cannot be disabled.
Therefore, the reporting interval does not remain constant throughout a given voice session, but its
average is the specified reporting interval.
Command
Purpose
Step 1
Router(config)# gateway
Enters gateway configuration mode.
Step 2
Router(config-gateway)# timer
receive-rtcp
timer
Enables the RTCP timer and configures a multiplication factor for
the timer interval. The argument timer is multiplied by the
interval that is set with the ip rtcp report interval command. The
valid range for the timer argument is 2 to 1,000. The default is 5.
the timer interval. The argument timer is multiplied by the
interval that is set with the ip rtcp report interval command. The
valid range for the timer argument is 2 to 1,000. The default is 5.
Step 3
Router(config-gateway)# exit
Exits gateway configuration mode.
Step 4
Router(config)# ip rtcp report interval
timer
Enters the minimum interval of RTCP report transmissions in
milliseconds. The valid range is 1 to 65,535.
milliseconds. The valid range is 1 to 65,535.