ASR TTS DNS error with Cisco CVP and VXML Gateway

I was struggling with setting up Nuance for one of my customers and while everything looked good on the Nuance side the connection between the gateway and Nuance failed right in the beginning. The very first thing is to setup some debugs on the gateway:

CCSIP SPI: SIP Call Message tracing is enabled (filter is OFF)
HTTP Client:
HTTP Client Main Process debugging is on
HTTP Client Sockets debugging is on
HTTP Client API Process debugging is on
HTTP Client Cache Module debugging is on
HTTP Client Messages debugging is on
HTTP Client Error debugging is on
HTTP Client Background Messages debugging is on
HTTP Client Cookie/Session debugging is on
MRCP:
MRCP client detail debugging is on

Next go follow the SIP trace and figure out where things start going wrong. We start with the initial invite for ASR.

3405261: Apr 14 23:51:30.451: //370879/B1BCCB67BB48/SIP/Msg/ccsipDisplayMsg:
Sent:
INVITE sip:asr@192.168.1.251:5060 SIP/2.0
Via: SIP/2.0/TCP 104.0.36.145:5060;branch=z9hG4bK8B21B80

From: <sip:+11235551234@us-east-va.sip.flowroute.com>;tag=47F96D40-1629
To: sip:asr@192.168.1.251

We get an OK, but notice the Contact address.

3405262: Apr 14 23:51:30.599: //370879/B1BCCB67BB48/SIP/Msg/ccsipDisplayMsg:
Received:
SIP/2.0 200 OK
Via: SIP/2.0/TCP 104.0.36.145:5060;branch=z9hG4bK8B21B80
Contact: <sip:mrcpserver@NUANCE10:5060;transport=TCP>
To: <sip:asr@192.168.1.251>;tag=75547221

From: <sip:+11235551234@us-east-va.sip.flowroute.com>;tag=47F96D40-1629

And then we get a failure.

3405264: Apr 14 23:51:30.639: %VOICE_IEC-3-GW: SIP: Internal Error (100, dns qry fail): IEC=1.1.128.7.51.0 on callID 370879 GUID=B1BCCB677DE111EABB48AD04394A93D1

Now after a bit of googling and reading Avaya documentation. The issue is that the Nuance Speech Server by default will use the hostname in its SIP header information and because DNS wasn’t working correctly the address mrcpserver@NUANCE10 doesn’t resolve. To fix fix DNS or open up your NSSserver.cfg and set the following:

server.mrcp2.sip.contact.useHostIPAddress VXIInteger 1

From this point forward Nuance will use the IP address for all SIP headers and you avoid DNS all together.

Remember, it’s always DNS. :)

~david

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