Forwarded call on UC520 is silent

[jon.aril.antonsen]

Hello.

I'm in progress of learning the UC500 series. I have so far got some really good help in here. And I hope I can get som e more.

The UC500 is connected to a SIP trunk with g711alaw support.

The problem now is call's that are forwarded. If i program forwarding of a call with the softbutton on the phone the call is silent. It will set up the call and I can answer the phone, but the call is silent, and there is no dial tone in the calling phone either.

[external phone (1)]------[Public]-----sip-----[UC520]------IP-----[internal phone (2)]

External phone number 51764610

Internal phone number 52223122 / int ext 202

On internal phone i have forwarded to 94849860.

I make a call to 52223122, and the call is forwarded so it starts ringing on the phone with number 94849860.

At this time there is no dial tone on the external phone.

I answer the 94849860 phone.

And then....silence.....

I have tried to hardcode codec on both in an out dial-peer with no luck

Attached is the current running conf and some debugs ccsip mess, ccsip err and voip ccapi inout

I hope someone is able to help me........Dilip are you there ;-)

Regards,

Jon

[jon.aril.antonsen]

Hi Paolo.

Sorry but that one is already configured. And I can't remove it either, that will result in a busy tone.

Jon

[dksingh]

Hi Jon,

Nops, nothing jumps out as abnormal in the debugs. Call is setting up fine and media

channels are negotiated as expected.

I think you need to check with your provider on whether they are sending any RTP or

not. For this call flow, UC is basically acting as IPIPGW/CUBE and is not going to

originate any RTP.It will simply pass RTP from one leg to another and vice versa.

The fact that we do not see any RTP packets in the packet capture or rtp debugs indicates

that none is hitting the UC and issue may be outside the bix we have been looking at.

One Q though....do u hear any ringback when u place the call that gets forwaded back to

PSTN over SIP trunk ?

DK

[emorivera2526]

I had this same exact issue with a SIP SP provider doing G711u.  As Felipe mentioned the problem was on the carrier side.  They are expecting the the UC520 to send RTP but the UC520 is only "relaying" the media it recieves.  Since the SP was not sending anything to the UC the UC was not sending anything back out on the forwarded call.  Their suggestion was terminating the original forwarded call to an IVR, then forwarding from there.  Well, of course this would work, but it was not a solution for all of your DNs.

Anyways, after much arguing and doing all the troubleshooting you have already performed, they moved me to another softswitch.  I was originally terminating to an Asterick platform.  They moved me to another softswitch and everything worked.  As an FYI - the provider I was using was Simple Signal.

In short - I could find no command on the UC, with TAC assistance, that would force the UC to originate RTP on a forwarded call.

Hope this helps

E

[dksingh]

Correct...that is what I am suspecting to be the case here as well.

There is no way to generate RTP on UC itself for forwareded calls

as UC is simply sitting in the middle relaying RTP and not really

originating any.

One interesting test would be to setup the call and then press digit

on one of the phone and see if there is any rtp/audio after that?

Debugs show that we are negotiating rtp nte and that should go in

the same media path as the voice.

DK

[jon.aril.antonsen]

Hi again Dilip.

So there is no problem on the UC.......hmmm.....could write some bad language here :-s

There is no dialback tone on the originating phone. It does not change anything bay pressing any byttons on either of the phones.

I will talk to the SP today. Hopefully they can configure the SP side to start transmitting the audio.

I'll be back with more info later on today.

Jon.

[jon.aril.antonsen]

Hi emorivera.

Thanks for the input.

I will try and talk to the SP and se if they can help me with this one.

Jon.

[jon.aril.antonsen]

I have a Q.

Fact: If I use a client side voice GW i can use H323.

Q. Can the UC500 be configured as a voice GW and take advantage of this, regarding the forwarding problem?

Jon.

Let me ask it in another way. Can I configure the UC520 to use H323 trunk, and will that solve the problem? And if this is possible, will it then change any of the features on the UC520?

Jon

Message was edited by: jon.aril.antonsen

[jon.aril.antonsen]

UPDATE:

Just talked to the SP. They are wil stop using H.323, so that's not gonna work. But they told me to call back on monday so that we could work together on this issue. I'm quite positive now, I think this problem will be solved on monday :-)

Jon.

[dksingh]

Hi Jon,

No ringback tone either....that itself tells you that they are not cutting any audio.

Which is strange as they do send back 183 with SDP info.

Yes UC can be configured for h323 but I won't go that route as UC is tested for

SIP trunking and not positioned as a h323 GW.

If you want to test h323, simply remove session protocol sip from the incoming

and outgoing dialpeers I mentioned and add allow-connect h323 to h323 under

voip service voip.

What you want ask your SP is if they can enable early media detection. Do you

know which SIP proxy they are using?

DK

[jon.aril.antonsen]

Hi Dilip.

Just for fun I tried H.323....with no luck. The call was just cut off and gave me a busy tone.

I don't know what SIP GW the SP are using, but I will get more info on monday. I will ask them to configure the GW as you proposed :-)

I don't think I will work this weekend...it's my wifes birthday tomorrow :-) :-) So monday it is.....

Have a nice weekend :-)

Jon

[dksingh]

Hi Jon,

Curious if you were able to work further on this with your SIP

SIP ?

Thx.

DK

[jon.aril.antonsen]

Hi Dilip.

For now I don't know much more. The SP is on the case, and I will hear from them hopefully next week.

I will update this case as sonn as I know anything more.

Jon

[peterputt]

Hi Jon,

Seems I have the same problem - did you manage to fix it? What have you done?

Regards,

Peter