SIGNALING AND RTP INCASE OF CAC AND AAR

[sachin.hello]

Hi Guys,

I want to know the Signaling and RTP flow . (Please check the attached snapshot)

The scenario is : CAC can not allow any new call over WAN.

Now if 2001 wants to call 3001, then what would be the flow of Signaling and RTP.

Both the phones are registered to CUCM and both WAN and PSTN are up. (Intracluster scenario)

Thanks and regards,

Sachin

[Jagpreet Singh · Accepted solution]

Hi Sachin,

    Here is how the signalling would take place:

> The IP Phone 1 (2001) will send a setup to the CUCM, who will cross check the call against the RSVP Manager process within the CCM service, which will reject the call sue to your CAC configuration.

> Thus, due to the AAR configuration, the CUCM will now match a Route Patter and send the call over PSTN. So, depending upon which protocol you are using for the PRI on the gateway, CUCM will send a MGCP CRCX or a H225 Setup to the gateway. Thus, eventually connecting the call across the PSTN.

> The Telco will send you an incoming setup message which will be passed over to the CUCM which will forward the setup request to IP Phone 2 (3001).

Here is how the RTP will flow:

> The Media negotiation will take place amongst IP Phone 1 and Voice Gateway. The call will go to the PSTN and come back, lets say on the same gateway and now a second leg of media negotiation will take place amongst IP Phone 2 and Voice Gateway.

> Thus if you run "show voip rtp connection" or " show voice call status/summary", you would see two channels occupied on the PRI and one connected with IP Phone 1 and the other with IP Phone 2.

Hope this helps. Please do feel free to ask any doubts which may arise and I shall try and answer them.

Regards,

Jagpreet

[sachin.hello]

Hello Jagpreet,

Thanks for your response.

Its been helpful.

Regards,

Sachin