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Tech Tip: Codec Preference control using CVP sig-digit





This document provides a sample Tech notes/Configuration for Codec Preference Control using CVP Sig-digit.


Problem Description


This section describes the symptoms of the problem and the main issue the document resolves.


We have a network scenario with Cisco Unified Customer Voice Portal (CVP), Unified Intelligent Contact Management (ICM) and Cisco Unified SIP Proxy (CUSP). Some of the sites we have only gateways and few sites we have gateways + agents.


Scenario 1: Calls coming from the site with only gateway, when we transfer call from CVP to Agent we need to use G729.


Scenario 2: Calls coming from the site with Ingress gateway and Agent, we need to use G711.


Now the issue here is, we have only one SIP trunk between CUSP and CUCM. CUCM is taking the region setting of the SIP trunk between CUSP and CUCM for agent transfer to use G729. How do we use specific codec G711 for the location calls having gateways and Agents?




CUCM refers to Cisco Unified Communications Manager

CUSP refers to Cisco Unified Sip Proxy

ICM refers to Cisco Unified Intelligent Contact Management

CVP refers to Cisco Unified Customer Voice Portal


Components Used

  1. Cisco Unified Communications Manager 8.0
  2. Cisco Unified Intelligent Contact Management 8.0
  3. Cisco Unified Customer Voice Portal 8.0




(1) From CUCM, define a new SIP security profile by different TCP or UDP port, then define second SIP trunk by this SIP security profile, effectively segregate calls from the same CUSP.


(2) If the calls are routed by the same CVP, you need to segregate calls by ingress gateway, this can be accomplished by CVP sig-digit feature, a special prefix that is assigned in ingress gateway. When CVP receives agent label from ICM, CVP sig-digit (a special prefix) will be prefix'edwith this digit, so CUSP can differentiate calls, and send to different SIP trunk of CUCM.


In point (1), two SIP trunks will help to segregate calls by codec G711 and G729. While in point 2, the sig-digits help you segregate calls by number patterns/locations.



Sample Configuration and Call flow:


Two gateway site as follows.


Site1: With GW1 and Agents


Site2: With GW2 only


Cisco Unified Customer Voice Portal (CVP), Cisco Unified Intelligent Contact Management (ICM), Cisco Unified Communications Manager (CUCM), Cisco Unified SIP Proxy Server (CUSP) all are located in data center.


On CUCM, we set up two SIP security profiles, one with TCP port 5060, second, tcp port 5061. Two SIP trunks (with 5060 and 5061 sip security profiles respectively); Three regions, Reg1 for agent ip phones; Reg2 for SIP trunk1 (5060); Reg3 SIP Trunk2 (5061). Reg1 and Reg2 use G711, Reg3 use G729.


For calls from Site1:


When calls come from site1 with DNIS1, and site2 with DNIS2, we will add a prefix 'p1' in site1 GW1, and 'p2' on site2 GW2 respectively. So the call flow for site1 is as below..


(DNIS1) -> GW1 -> (P1+DNIS1) -> CVP -> (DNIS1) -> ICM -> (agent label) -> CVP -> (P1+label) -> CUSP -> SIP trunk1 (5060) -> CUCM -> agent phone (site1)


Since calls coming from SIP trunk1 (5060), CUCM will negotiate G711 for this call. (From GW1, codec is negotiable on dial-peer).



For calls from Site2:


(DNIS2) -> GW2 -> (P2+DNIS2) -> CVP -> (DNIS2) -> ICM -> (agent label) -> CVP -> (P2+label) -> CUSP -> SIP trunk2 (5061) -> CUCM -> agent phone (site1 or any other site than Site 2 as there are no agents on Site 2)


CUCM negotiates G729 for this call.


From above example, you could see, CUSP can route calls to different SIP trunks by sig-digit (P1 or P2) depending on where the calls come from. CUCM can decide which codec to be used based on which SIP trunk the call comes in from.



Related Information


Community Member

With new CVP enhancements like LBCAC Queue at Edge and mixed-codec supports, is it always the only solution ?