Cisco Cisco IOS Software Release 12.4(6)T

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This feature module describes the SIP: Cisco IOS SIP Gateway Signaling Support Over TLS Transport 
feature which implements the Transport Layer Security (TLS) protocol on the Transmission Control 
Protocol (TCP) transport for Cisco IOS SIP Gateways. The feature leverages the existing SIP gateway’s 
support of the public-key infrastructure (PKI) (for certificate management) and utilizes TLS 
functionality to provide SIP signaling over TLS transport. The use of PKI on the Cisco IOS software 
requires that the clock on the session initiation protocol (SIP) gateway be synchronized with the network 
time to ensure proper validation of certificates.

The SIP: Cisco IOS SIP Gateway Signaling Over TLS Transport feature provides security only to the 
device authentication and data encryption of SIP signaling information at the transport layer of the Open 
System Interconnection (OSI) model. The authentication of the SIP user itself at the application level is 
done using the Digest Mechanism Implemented by the SIP Gateway Authentication feature.

Your Cisco IOS software release may not support all of the features documented in this module. To reach 
links to specific feature documentation in this module and to see a list of the releases in which each feature is 
supported, use the 

.

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