What are the two primary roles of the PSTN and voice gateway in the Unified...

The PSTN (Public Switched Telephone Network) and voice gateways are the entry points for calls into a Cisco contact center. Understanding their roles is foundational to CCE architecture and call flow design.

Why the Correct Answer is Right: A is correct because voice gateways can perform digit manipulation through dial peer configurations—modifying DNIS, ANI, or trunk group digits before passing call information to CVP/ICM. This is a documented gateway capability in Cisco IOS. C is correct because the PSTN is responsible for transporting the inbound call from the originating caller's phone to the contact center's ingress voice gateway—this is its fundamental architectural role.

Why Each Incorrect Answer is Wrong: B is wrong because IVR functionality is provided by CVP and VVB, not the voice gateway itself. D is wrong because routing calls to agents is the responsibility of ICM (the routing engine), not the PSTN. E is wrong because the voice gateway delivers calls to CVP; ICM handles the actual routing decision to agents.

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