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Syed Shahzad Ali

ASR/TTS Port and License Utilization in CVP

ASR and TTS licenses are not sold by Cisco; they must be acquired directly from the vendor. ASR and TTS port licenses are carefully enforced for all the vendors currently supported by Unified CVP. The license is checked out the moment a call needs to use it, and it is reserved until the call leaves the VoiceXML gateway.

Please Note: This behavior is different than VXML Server licenses.

Also, ASR and TTS licenses are independent: a call checks out an ASR license when it first needs to use ASR services, and a TTS license when it first needs to use TTS services.

If you plan to move calls from self-service to queuing functionality, you will most likely want to release the ASR and TTS licenses. However, Unified CVP makes no distinction between a call that is at the VoiceXML gateway for self-service purposes and one that is there to play queue music.

It does not know that the call has progressed from self-service to queuing services. The same VoiceXML gateway session remains active across the transition, so any ASR and TTS licenses that were obtained in the first phase are not automatically released.

Workaround to Release ASR/TTS License in Queuing

You can, however, force the licenses to be released by causing the call to be removed from the VoiceXML gateway and then redelivered there as a new VRU leg call.

Removing it from the VoiceXML gateway releases the ASR and TTS licenses, and redelivering the call makes it immediately available to play queue prompts again, but this time without ASR and TTS licenses.

You can accomplish this result by transferring to a bogus label causing a re-query to ICM and placing an explicit SendToVRU node or TranslationRouteToVRU node ahead of the Queue node in ICM scripting to release the ASR/TTS licenses.

ASR/TTS Port and License Utilization in IP-IVR (UCCX)

For IP-IVR, the vendor licensing works as follows:

  • Each MRCP session consumes one relevant vendor license. If it was an ASR session, then it would consume one ASR license. If it was a TTS session, it would consume one TTS license.
  • For ASR, IP-IVR (other names of the products are CRS/UCCX/IPCCX) creates the session the first time ASR is used in a call and the session remains up until the call is ended.
  • For TTS, IP-IVR creates a session for each separate TTS prompt to play. When a TTS prompt is finished playing, then the session is terminated.
  • Since TTS Prompts are played one after another, this has the effect of taking and releasing a TTS license over and over even during a single call. However, in general, only one (at most maybe two if there is a delay in closing a session) TTS licenses would be consumed at any given moment within a single call.

Keep in mind that this has nothing to do with IP-IVR Channel licenses.




A) Is it correct to say that if we do not have a bogus label that the ASR/TTS license will be released after the call reaches an agent or after the call is completed?

B) Have there been any enhancements in this area other than using the bogus label node?

C) Is it a must to use the explicit SendToVRU node after the bogus label node?

D) We use a bogus label but do not have a explicit SendToVRU. The call is armed with Post Call Survey but we get an alarm (SIP_ERROR_SNMP: B2BUA is not configured with a Post Call Survey dialed number) however with no side effects. Has one successfully dealt with avoiding this alarm


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