для Cisco Cisco IOS Software Release 12.2(15)ZJ

Prior to Cisco IOS Release 12.2(15)ZJ, when a call was redirected, the SIP gateway would send a “302 
Moved Temporarily” message. The first longest match route on a gateway (dial-peer destination pattern) 
was used in the Contact header of the 302 message. With release 12.2(15)ZJ, if multiple routes to a 
destination exist for a redirected number (multiple dial peers are matched), the SIP gateway sends a “300 
Multiple Choice” message and the multiple routes in the Contact header are listed.

A new command has been added to give users the flexibility to choose the order in which the routes can 
appear in the Contact header.

SCCP IP phones do not support in-band DTMF digits; they are capable of sending only out-of-band 
DTMF digits. To support SCCP devices, originating and terminating SIP gateways can use Cisco 
proprietary NOTIFY-based out-of-band DTMF relay. In addition, NOTIFY-based out-of-band DTMF 
relay can also be used by analog phones attached to analog voice ports (FXS) on the router.

NOTIFY-based out-of-band DTMF relay sends message bidirectionally between the originating and 
terminating gateways for a DTMF event during a call. If multiple DTMF relay mechanisms are enabled 
on a SIP dial peer and are negotiated successfully, NOTIFY-based out-of-band DTMF relay takes 
precedence. 

The originating gateway sends an Invite message with SIP Call-Info header to indicate the use of 
NOTIFY-based out-of-band DTMF relay. The terminating gateway acknowledges the message with an 
18x/200 Response message, also using the Call-Info header. The Call-Info header for NOTIFY-based 
out-of-band relay appears as follows: 

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

Duration is the interval between NOTIFY messages sent for a single digit and is set through the 

 command. 

After the NOTIFY-based out-of-band DTMF relay mechanism is negotiated by the SIP Invite and 
18x/200 Response messages, whenever a DTMF event occurs the gateway sends a SIP NOTIFY message 
for that event. In response, the gateway expects to receive a 200 OK message. 

The NOTIFY-based out-of-band DTMF relay mechanism is similar to the DTMF message format 
described in RFC 2833. It consists of 4 bytes in a binary encoded format.

9

5051

event

unused

E R

duration

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7