Configuration on CVP Call Server SIP Service

[4deepakkaushikk]

Dear Experts,

request your help, actully i want to understand that when call comes from ingress gateway we have dial-peer to send call to cvp call server sip service. then how cvp call server sip service receive call and send call to icm service. what machanism sip service use. do we need to make some configuration on ops console to receive call from ingress gateway and handover call to icm service.

Thanks,

Deepak

[Sasikumar Divvela]

I am not very sure about cvp inter subsystem communication  but AFAIK, when call comes to cvp it checks the length of the number , if it is less than or equal to the DNIS length configured in CVP oamp (under icm sub system) it will send a new call request to ICM VRU PG.

This is the only config in CVP i usually do in comprehensive call flow.

[Ayodeji Okanlawon]

Deepak,

There are three main subsytem within CVP

1. SIP B2BUA

2. ICM

3. IVR

When a call arrives at CVP, from Ingress gateway/vxml gateway, the call is sent to the SIP B2B-UA.

Once the SIP B2B-UA receives the call, CVP determines if this is a new call or a VRU call before taking next action. I will explain how CVP knows if its a new call or VRU call later. 

Next CVP Sends the call to the ICM subsystem, the ICM subsytem then sends the call to VRU PIM ( this is the process that sends the call to ICM)

So its like this

Ingress gateway----SIP--------->CVP [SIP-B2B-UA---->ICM] ---------VRU-PIM-------->ICM Router

++ call flow example ++

CVP Call routing to ICM ( Max length of DNIS configured on CVP=10)

1. Ingress Gateway sends INVITE to CVP
2. CVP Returns with 100 TRYING
3.CVP checks if it is new call or VRU call. It checks the DNIS length. If the DNIS length is less or equal to the “Max DIGIT” define in ICM subsystem, CVP knows it is new call.

4.CVP Sends NEW_CALL request to ICM

5. ICM PG will convert the NEW_CALL to Route Request and send to ICM Router

++ a few things will happen in ICM router and then ...

ICM Router picks the label defined for CVP RC, generate Correlation ID and sends to CVP

6.CVP gets the label 9999999999 and corid 10. It combines it, looks for route.

+++ Now  a lot of things happen here but at the end...

7.VXML Gateway now sends NEW_CALL HTTP request to CVP with DNIS=99999999991017.

Now, Since the DNIS is greater than the “max digit” defined on CVP which is 10, CVP knows it’s a VRU returning call, it split the label and correlation ID, sends a REQUEST INSTRUCTION to ICM with Label = 9999999999, corid=1018.

Based on the corid=10, icm knows which script which node the call was waiting for. So it continues to execute next step which is “Run Ext Script”.

One of the important piece of configuration on CVP is the "MAX length of DNIS"

For VRU call to work, the “MAX length of DNIS” and VRU label length must match. When the HTTP requests comes back from VXML Gateway with VRU label and Correlation ID together, CVP splits VRU label and Correlation ID based on the “MAX length of DNIS”. If it doesn’t match with what ICM is configured for VRU length, CVP will split the Correlation ID wrong, which eventually will be rejected by ICM