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Community Member

call flow

Hi experts, anyone who knows of a documents or links I can refer to know what happen if I initiated a call from my CIPC to local PSTN or vice versa? and how can I see the call progress, logs, etc. that can give idea how the call traverses the network. thanks in advance


Re: call flow

This is fairly easy.

The phones will communicate on a signaling level to the device they are registered to. For CIPC this happens to be the SCCP protocol, and you will have a Callmanager.

The phone will maintain registration and sending call routing and signaling information directly to Callmanager via TCP 2000.

When a call is placed and audio is to be played, the audio will be directly between your gateway with the PSTN connection and your IP phone. This means that the audio doesn't flow through CUCM.

In order for the gateway to know where to send the audio, and to maintain its own registration, it also runs a protocol. This is different from phones, and will be SIP/MGCP/H323.

The phone will talk SCCP, exchange IP addresses with Callmanager, Callmanager will talk the gateway protocol and tell it where to send the media, and then the RTP packets flow directly.

Given - this is the best-case simple scenario. When you put things like transcoders, MTPs, and forwards and transfers things get much uglier very quickly.

For more information, I would try picking up the CVoice book.



Community Member

Re: call flow

Thanks for that valuable information you have shared. Another thing how to know from the gateway/gatekeeper for a call that has been placed? what is the command, also, which part of CM i will know that a call has been placed that will tell me where it originates. thanks

Community Member

Re: call flow

Hi just some additional questions, say I place a call using CIPC going to a local PSTN no. how to trace that call? From CM to gateway..and vice versa. What are the useful commands i will use in gateway and CM? This what I want to know how the placed call traverses to the network going to the called party. Thanks!

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