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Cisco 3900 Series, Cisco 2900 Series, and Cisco 1900 Series Integrated Services Routers Generation 2 Software Configuration Guide
Chapter       Unified Communications on Cisco Integrated Services Routers
Applications and Application Interfaces (APIs)
Signaling and Media Authentication and Encryption
The Media and Signaling Authentication and Encryption Feature for Cisco IOS MGCP Gateways feature 
provides support for Cisco Secure Survivable Remote Site Telephony (SRST) and voice security features 
that include authentication, integrity, and encryption of voice media and related call control signaling. 
See Media and Signaling Authentication and Encryption Feature on Cisco IOS MGCP Gateways at 
Cisco.com for configuration information, 
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t11/feature/guide/gtsecure.html.
The Media and Signaling Encryption (SRTP/TLS) on DSP Farm Conferencing feature provides secure 
conferencing capability for Cisco Unified Communications Manager (Unified CM) networks, including 
authentication, integrity and encryption of voice media and related call control signaling to and from the 
digital signal processor (DSP) farm. 
See Media and Signaling Encryption (SRTP/TLS) on DSP Conferencing Farm at Cisco.com for 
configuration information, http://www.cisco.com/en/US/docs/ios/12_4t/12_4t15/itsdsp.html.
See SIP: SIP Support for SRTP at Cisco.com for configuration information, 
http://www.cisco.com/en/US/docs/ios/12_4t/12_4t15/srtpstub.html#wp1008975.
Virtual Route Forward 
Virtual Route Forward (VRF) is the technique to create multiple virtual networks within a single network 
entity. In a single network component, we can create multiple VRFs to create the isolation among each 
other. In our regular deployment of Unified Communication, we create different VLANs for voice and 
data to separate traffics. This is Layer-2 virtualization. In conjunction with VAN support, Cisco UC also 
supports Layer-3 virtualization through VRF for both voice and data.
In a typical UC deployment, hard phones are typically in Voice Segments and PCs are in Data Segments. 
PCs are inherently un-trusted devices in the network. Mechanisms based on’s rely on port numbers and 
there is no way to ensure only ‘trusted’ media enters UC Segment. VRF implementations in ISR can 
create single voice network and multiple data networks, which consolidate voice communication into 
one logically partitioned network to separate voice and data communication on a converged multi-media 
network. 
To configure Virtual Route Forward features, see Virtual Route Forwarding Design Guide at: 
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/vrf/design/guide/vrfDesignGuide.html.
Applications and Application Interfaces (APIs)
The Cisco 3900 series and Cisco 2900 series ISRs support the following applications and application 
interfaces:
• Cisco Unity Express, page 180
• Voice XML, page 180
• Hoot-n-Holler, page 181
• Hoot-n-Holler, page 181
• Cisco Application Extension Platform, page 181
• APIs, page 181