Cisco Cisco IOS Software Release 12.4(2)XB6

The control media-cut through on SIP 18x response feature provides the ability to send media backward 
even before the call is established. So instead of allowing media to flow both ways only after the call is 
established, this feature allows the remote side to send a personalized ringback tone (usually music) as 
a response even before the call is established. 

Doing only backward media cut-through on 18x messages affects the digit collection process (RFC 2833 
mechanism) before the call is connected (SIP 200 OK message is sent and accepted). Since most of the 
SIP IVR deployments use RFC 2833 to collect digits before a call is connected, the current default 
behavior (bidirectional media cut-through on 18x) is retained.

The Pass data in SIP REFER to triggered INVITE feature provides the ability to map SIP REFER 
message data into SIP INVITE messages. This new feature allows you to send customer-specific 
information to triggered SIP INVITE messages using Call-Info as the URL header of the SIP REFER-TO 
message. Further, this feature allows the gateway to take SIP REFER data and create a new SIP INVITE 
message to a new destination when a call is being placed to an Interactive Voice Response (IVR) 
endpoint and the IVR refers the call to an agent or to another IVR system.

There are no new hardware features in this release.

There are no new software features in this release.

For information regarding the features supported in Cisco IOS Release 12.4T, see the Cross-Platform 
Release Notes links at : 

The following limitations and restrictions apply to the Cisco IAD2801 series

Fixed Configuration Platforms Supporting Specific Cards, page 7