Can CUCM 8.6 send 183 with SDP?

[n.kondratyev]

Hi all,

Can anybody please advise if CUCM 8.6 can send 183 with SDP (or 180 with SDP) in reply to Invite incoming via the sip trunk?

I tried to find something in the documentation, but alas...

Thanks in advance,

Nikolay.

[Ayodeji Okanlawon]

Yes CUCM can send 183 with SDP but it cant send 180 with SDP..

When early media needs to be delivered to SIP endpoints prior to connection, Cisco Unified Communications

Manager always sends a 183 Session Progress message with SDP. Although Cisco Unified Communications Manager

does not generate a 180 Alerting message with SDP, it does support the 180 Alerting message with SDP when

it receives one.

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"'Nature is too thin a screen, the glory of the omnipresent God bursts through it everywhere"-Ralph Waldo Emerson

[n.kondratyev]

Hi,

thanks for the answer.

I've also seen this words in the manual.

But... my understanding is that this is about the condition when cucm gets 183 or 180 with SDP and delivers 183 with SDP to endpoint. I managed to make this case to work.

My case is different: invite is coming to cucm from the sip trunk, corresponding phone is ringing (phone sends 180 without SDP to CUCM), and i need to make CUCM to send early media to trunk in reply to original invite.

Is this possible? If yes, can you please advise how do i do it?

Small addition: i only need the above functionality in certain scenario when third party is making blind transfer to CUCM user.

Thanks in advance,

Nikolay.

[Ayodeji Okanlawon]

Are you using CUBE in your system? I assume that your cucm is configured for delayed offer? If you are using CUBE, you can configure it to do ealry offer and it will generate 183 with SDP when sending session progress even if cucm is sending 180 without SDP.

You said you managed to make this case to work? Does that mean you are okay now..

How are you affected by blind transfer? Can you describe the problem you are having?

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"'Nature is too thin a screen, the glory of the omnipresent God bursts through it everywhere"-Ralph Waldo Emerson

[n.kondratyev]

There were two different problems.

1.CUCM user calls mobile phone that is switched off. Instead of "subscribes's phone is switched off or out of the coverage" announcement from mobile operator (which is sent in early media) user hears silence.

This problem is solved.

2. the second problem is as following: call is coming to a callcenter (Genesys). And callcenter operator after a while makes blind transfer to CUCM user. And calling user hears silence instead of ringback tone. The thing is that callcenter in this scenario reckons on SDP in 183 or 180 for providing rbt to calling user. Thats why i'm looking if CUCM can send early media to trunk (say play moh file).

Thanks and regards,

Nikolay.

[Ayodeji Okanlawon]

As far I know This is not a CUCM problem. If genesis is the one doing the blind transfer then genesis needs to provide rbt or moh during the xfer. If CUCM is the one doing the blind transfer, cucm uses Annunciator to play ringback during blind transfer. During cucm transfer the sip trunk needs to have ANN in its MRGL.

Out of curiosity..what was the resolution to the first problem. Was your provider sending 183 with SDP to cucm on that call?

This is the rule used to determine who plays ringback or not..

When 183 with SDP or 180 with SDP is received, the person sending it must provide either ringback tone/busy tone. CUCM cuts through the media to listen to what the provider is sending. When 180/183 is recieved by cucm without SDP, cucm tells the phone to play ringback locally.

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"'Nature is too thin a screen, the glory of the omnipresent God bursts through it everywhere"-Ralph Waldo Emerson

[n.kondratyev]

I agree that according to usual procedures it is not CUCM responsibility, the one who is doing transfer should provide rbt.

But if CUCM could provide what i asked for, that would solve my problem....

Regarding the first problem: yes provider is sending announcement in unidirectional voice channel without actual answer.

And sip-pri gateway (2921) translated that into 180 with sdp.

Rgds,

Nikolay.