CVP Port Usage
Often time when sizing CVP, the design engineers have this concern that if the CVP port remain utilized during all the call duration? Or instead is the port released as soon as the calling customer is connected with the agent?
The CVP port usage is dependant on the number of active calls in the system that is either in the CVP queue or reciving self-service IVR treatment. If there is a call in the system, it uses a CVP port.
CVP remains in the loop
The explanation to this behavior is that typically, the CVP remains in the loop for further call control and thats why the CVP port is being utilized all the time. But there is a transfer mechanism for H.323 calls that behaves in a similar manner to SIP Refer. This feature allows Unified CVP to remove itself from the call, thus freeing up call control ports. Using this feature, the call can be queued at the VoiceXML gateway and then sent to an agent on Cisco Unified Communications Manager.
Unified CVP cannot execute further call control operations after this kind of transfer has been executed; however, Unified CVP Survivability can still be used for failure recovery in this scenario. This feature can be used in both Comprehensive and Call Director call flow models, and it is available only for PSTN-originated calls via a Cisco IOS gateway running the Unified CVP Survivability service.
You should also note that the Unified CVP Port License is only for calls that are receiving IVR treatment, such as calls in self-service or in queue. Calls that are connected to agents do not use a Unified CVP Port License but instead use a call director ports license. This call director port license is free of charge when the agent is UCCE agent.
