Cisco Cisco IOS Software Release 12.2(15)ZJ

To configure the maximum interval between two consecutive NOTIFY messages for a particular 
telephone-event, use the notify telephone-event command in SIP user-agent configuration mode. To 
reset the interval to the default, use the no form of this command.

notify telephone-event max-duration time

2000 milliseconds

SIP user-agent configuration

The notify telephone-event command works with the dtmf-relay sip-notify command. The 
dtmf-relay sip-notify command forwards out-of-band DTMF tones by using SIP NOTIFY messages. 
The notify telephone-event command sets the maximum time interval between consecutive NOTIFY 
messages for a single DTMF event. The maximum time is negotiated between two SIP endpoints and the 
lowest duration value is the one selected. This duration is negotiated during call establishment as part of 
negotiating the SIP-NOTIFY DTMF relay. 

The originating gateway sends an indication of DTMF relay in an Invite message using the SIP Call-Info 
header. The terminating gateway acknowledges the message with an 18x/200 Response message, also 
using the Call-Info header. The set duration appears in the Call-Info header in the following way: 

Call-Info: <sip: address>; method="Notify;Event=telephone-event;Duration=msec" 

For example, if the maximum duration of gateway A is set to 1000 ms, and gateway B is set to 700 ms, 
the resulting negotiated duration would be 700 ms. Both A and B would use the value 700 in all of their 
NOTIFY messages for DTMF events. 

The following example sets the maximum duration for a DTMF event to 500 ms.

Router(config)# sip-ua

Router(config-sip-ua)# notify telephone-event max-duration 500

max-duration time

Time interval between consecutive NOTIFY messages for a single DTMF 
event, in milliseconds. Range is from 500 to 3000. Default is 2000.

12.2(15)ZJ

This command was introduced.