topic Re: SIP VC endpoint call flow in IP Telephony and Phones

SIP VC endpoint call flow

pramith — Tue, 12 Nov 2019 15:53:15 GMT

Hi ,

Can someone explain me how does the SIP point to point VC call works.

Example: SIP endpointA at Bangalore and Endpoint B at Pune.

How does call get initiated and how it flows,

Re: SIP VC endpoint call flow

Dan Lukes — Tue, 12 Nov 2019 18:55:55 GMT

It seems you are speaking about most simple SIP call case (video call and audio calls use same setup procedure, just different codecs are used) . I'm unsure what's unclear to you.

I assume you are familiar with SIP basics. Learn SIP principles from RFC3261 if my assumption is wrong.

Re: SIP VC endpoint call flow

pramith — Wed, 13 Nov 2019 16:59:00 GMT

The document which you have sent is understand the sip in depth,

i just want to know the flow.... like...point A wants to call point B.

1)Does the request sent to CUCM first?

2)What cucm will do?

3)When DNS get involves in this.

4)What DNS will do

please explain with example .... take your time... i have gone through google... but i found complex articles only........

These questions may be simple to you, as i am not from network domain, if u explain me the flow only i can understand...

Re: SIP VC endpoint call flow

Dan Lukes — Wed, 13 Nov 2019 21:20:56 GMT

1) Does the request sent to CUCM first?

2)What cucm will do?

It depends on configuration. In most simple case, there is no CUCM at all, thus it do nothing.

3)When DNS get involves in this.

4)What DNS will do

It depend on configuration. In most simple case, IP address is dialed, DNS is not used at all thus it do nothing.

These questions may be simple to you

It's no longer simple question, it's generic question. Thus it can't be answered by simple example.

Just "SIP VC endpoint call flow" is simple question. Originator sends SIP invite with sdp directly to called party identified by IP dialed by user. Neither CUCM nor DNS is used. Called phone responds with SDP. Originator sends ACK, call is considered connected, audio and video data are translated according SDP. Well, even this question can't be answered with no knowledge of configuration, as content of both SDP depends on configuration.

Complex scenario with CUCM is not simple question. And I'm no expert on it as our phone network uses no CUCM.

Consider to disclose purpose of your question. It may help an expert to answer.