Cisco Cisco IOS Software Release 12.2(4)YH

The following sections list the new features supported by the Cisco 1700 series routers for 
Release 12.2(4)YH.

The following sections describe the new software features supported by the Cisco 1700 series routers for 
Release 12.2(4)YH.

QSIG protocol support allows Cisco voice switching services to connect private branch exchanges 
(PBXs), key systems (KTs), and central office switches (COs) that communicate by using the QSIG 
protocol. The QSIG protocol is becoming the standard for PBX interoperability in Europe and 
North America.

The X.25 standard defines a Closed User Groups (CUG) as an available network security feature. The 
Terminal Line CUG Security feature extends existing X.25 CUG capabilities that allow PAD access 
devices (TTY, VTY, CON, and Aux) to be configured for CUG security enforcement. Using the 
Cisco implementation of CUGs, you can configure access parameters at the X.25 network POP (DCE 
interface) boundary. 

For information regarding the features supported in Cisco IOS Release 12.2 T, refer to the 
Cross-Platform Release Notes and New Feature Documentation links at the following location on 
Cisco.com:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122relnt/xprn122t/index.htm

This URL is subject to change without notice. If it changes, point your web browser to Cisco.com, and 
click the following path:

:

 Technical Documents

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:

 Release 12.2

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 Release Notes

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Cross-Platform Release Notes (Cisco IOS Release 12.2T)

The following sections contain important notes about Cisco IOS Release 12.2(4)YH that can apply to 
the Cisco 1700 series routers. (Also, see the 

Cisco 1760 and 1760-V router fans are always on. However, the fans in Cisco 1720, 1721, 1750, and 
1751 routers stay off until thermally activated.