Question

A company discovers that an external caller reached the corporate operator, was transferred to voicemail, and used the auto-attendant to dial an international premium-rate number, generating large toll charges. The security team asks you to prevent Cisco Unity Connection and CUCM from allowing inbound PSTN callers to place outbound calls through the system. Which CUCM configuration most directly blocks this specific toll fraud vector?

Accepted Answer

Assign a restrictive Calling Search Space to the voicemail ports (CTI route point/ports) so it cannot reach partitions containing international route patterns

Answer

Enable Digest Authentication on all SIP phones so unauthenticated devices cannot register

Answer

Increase the Max Forward Unregistered Calls to Internal service parameter to reroute suspicious calls

Answer

Configure a SIP trunk with Delayed Offer to force renegotiation of the transferred call media