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New Member

Call Flow Process

I am looking for some help in finding a call flow process steps or diagram.

For example:

A phone goes off hook and contacts the Publisher via XYZ protocol

The Publisher then does this and that

A number is pressed on the phone and this happens

I hope that makes since. I'm just looking for detailed step-by-step lists or diagrams about how the phones, servers, etc. work together in different scenarios. I've looked around for awhile have not found anything yet.




Re: Call Flow Process

Ok.  So, here are the basics.  1st - the Publisher should typically NOT have phones registered to it.  The Subscriber is the primary call processing node.  So, your example would be this:

Phone goes off --> SCCP Off-Hook message goes to Subscriber

Subscriber says "Ok, you're off-hook you should hear dial tone" --> SCCP message goes to phone telling it to play dial tone

Phone dials 7035551212 --> For each digit, a SCCP message is sent to the Subscriber and it collects this digits for call processing, it finds a match

Subscriber sends a SCCP message to the phone with 7035551212 and tells the phone to ring

Subscriber sends a SCCP message to the dialing phone telling to to play ringback tone

Each party picks up and SCCP messages are received by the Subscriber and at this time, it sends each phone a Start Media Transmission message

At this point each phone opens up a channel to send/receive RTP streams directly to each other

The subscriber is not involved in the call flow unless one of the phones invokes a supplementary service (hold, transfer, etc) and then when each phone hangs up, the Subscriber sends a message to each phone to tear down the RTP channel between each phone.

Basic, but that's it.


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New Member

Re: Call Flow Process

Thanks, that is helpful. Do you know where this might be discussed in more detail in official documentation?

I'm also looking for more examples like calling locally outside the network, calling international, failover in a remote office.

Message was edited by: travisbarden

Cisco Employee

Re: Call Flow Process

Try this:

Using Call Flows to Resolve Call Processing  Problems

You would need to read CCVP study material which also has this.

Otherwise just pull up some CUCM detailed traces and you'll see the whole process.



If this helps, please rate



if this helps, please rate
New Member

Re: Call Flow Process

Thanks Java! I'm working on my CCNA and then CCVP.

FYI - I found this link for ver 7