Cisco Cisco IOS Software Release 12.2(2)XK

Modem pass-through offers the following benefits:

Detecting modem tones

Passing modem signals over the WAN

Performing proper switchover to pass modem traffic on a bearer channel

Detecting modems at speeds up to V.90

The Cisco ICS 7750 allows you to pass through fax signals on one line at a time. To use the fax 
pass-through feature, the gateway must be configured to detect the fax tone and switch codec.

When you are using G.729 on one port, the other port automatically uses the G.711 protocol. Use the 
same codec type for both the originating gateway and the terminating gateway. The g711ulaw codec 
is required for T1, and the g711alaw codec is required for E1. 

The following sections contain important notes about Cisco IOS-related issues that can apply to the 
Cisco ICS 7750. (Also, see the 

.)

In a network environment that uses Cisco 2600 series routers, Cisco 3600 series routers, and 
Cisco ICS 7750s, to avoid intermittent call setup failures all platforms should run Cisco IOS Release 
12.2(2)XK2 or later.

All of the MRP and ASI cards in a Cisco ICS 7750 must run the same Cisco IOS image.

Caveats describe unexpected behavior or defects in Cisco IOS software releases. Severity 1 caveats are 
the most serious caveats, severity 2 caveats are less serious, and severity 3 caveats are the least serious 
of these three severity levels.

All caveats in Release 12.2 T are also in Release 12.2(2)XK2. For information on caveats in Cisco IOS 
Release 12.2 T, refer to the 

document. For information on caveats 

in Cisco IOS Release 12.2, refer to the 

document. These documents 

list severity 1 and 2 caveats, and are located on CCO and the Documentation CD-ROM.