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Cisco IOS router as PSTN gateway for MS Speech Server IVR applications

I am having issues in getting a Cisco 2811 router to function properly with Microsoft Speech Server 2007. We have the router configured as a very simple gateway for this purpose. It takes inbound calls and forwards the calls on to the Speech Server just fine, but when performing outbound calls we run into an issue. The Speech Server begins playing it's IVR application to the caller seemingly immediately upon the router accepting the SIP invite message. Of course, the router has not setup the call to the PSTN destination yet and the IVR application may be finished playing it's message by the time the called party even picks up. I don't know what I'm missing here but I have to think it is something very simple. I had read about blind versus attended transfers but so far have not been able to figure out if that is the issue and/or how to configure it for an attended transfer if that is the issue.

Any assistance or ideas here would be appreciated.

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Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

OK, I'm shooting in the dark here, so take this with a grain of salt and ignore if you'd like.

I think the issue is that you are using an FXO port. If it were a digital trunk, especially PRI, this wouldn't be a problem. The issue is that the far end is generating the ring-back, and the router assumes that you want to hear the ringback, so it sets up the RTP stream right away. The issue is the E_HTSP_VOICE_CUT_THROUGH option in the FXO's call control debug. I think you may be able to disable that by using the 'no auto-cut-through' in the FXO voice port config mode. I believe that will force the router to wait until the call is answered before opening the RTP stream.

Let me know if that works or if you've solved it some other way.

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Community Member

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

Here is a copy of the config we have running for the proof-of-concept lab at the moment.

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

Can you turn on 'debug ccsip messages' and capture the output during a call? That would help clarify exactly what is happening.

Community Member

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

Here is a capture I did the other day. I had a few other ccsip debugs on as well.

Thanks for trying to help me out here.

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

OK, I'm shooting in the dark here, so take this with a grain of salt and ignore if you'd like.

I think the issue is that you are using an FXO port. If it were a digital trunk, especially PRI, this wouldn't be a problem. The issue is that the far end is generating the ring-back, and the router assumes that you want to hear the ringback, so it sets up the RTP stream right away. The issue is the E_HTSP_VOICE_CUT_THROUGH option in the FXO's call control debug. I think you may be able to disable that by using the 'no auto-cut-through' in the FXO voice port config mode. I believe that will force the router to wait until the call is answered before opening the RTP stream.

Let me know if that works or if you've solved it some other way.

Community Member

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

I really appreciate your input here. I have a TAC case open on it and have our MS developers trying to work a case on that side.

This does make sense and the FXO port is just there for testing. I tried to put the change in that you suggest here but it's not an available configuration setting on the the voice ports for me. I verified that it is still a valid configuration setting in 12.4T code from the Command Lookup page so I'm not certain why I do not see it.

Anyways, if you have any further insight here, feel free to share it as I would really like to figure it out just out of principal even though I do have a PRI circuit due next week to use for the production solution here.

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

Trying adding in the following commands:

voice service voip

allow-connections h323 to sip

allow-connections sip to h323

sip

There needs to be a return path also back to the 2811 Gateway from the OCS server. If you do not define, the SIP packets from the OCS will die out.

If Im not mistaken, the call does not come directly from the speech server, it comes from the mediation server. So the calls needs to go to/from the same end point.

Community Member

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

I appreciate the suggnestion here but the Speech Server piece of OCS is somewhat seperate and does not require a Mediation server or anything other than SIP so I don't think this will do anything. The calls are going through successfully. It's just that the OCS (Speech Server) is playing the IVR Text-to-Speech message immediately upon the call being placed and so it's partially done or completely done by the time the destination phone rings.

My case with TAC has been escalated as of today as well so hopefully I'll get this figured out soon. Otherwise, our PRI circuit for the permanent solution should be here tomorrow and that may resolve things.

Community Member

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

In-case anyone was following this, the diagnosis by ccharlebois was confirmed by TAC. Here is the official response I got on this issue.

You aren't going to be able to do what you want to do on an FXO port. Because the FXO is connected right at setup (so the user can hear ringback), there is no way to signify via signaling when the PSTN user has actually answered the call. FXO ports don't have the provisioning to notify the SIP server when a user has actually picked up.

The only way to get it to work on the FXO would be if you had the IVR loop a message like 'press 1 to hear the message') so that when the user answers and presses 1, then the audio message starts playing.

With a PRI, you will be fine, as the PRI will use an ALERTING state for ringback, and won't move to a connected state until the PSTN user answers, accomplishing what you want.

Re: Cisco IOS router as PSTN gateway for MS Speech Server IVR ap

Awesome! Thanks for the follow up on this! I always wonder if you used FXO to SIP if there was any issues and apparently there! (at least for IVR apps)

Cheers!

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