An administrator is asked to implement toll fraud prevention in Cisco UCM, specifically to restrict off- net to off-net call transfers How is this implemented?

Time-of-day routing controls when certain call routes are available, which helps with general call routing, but it does not specifically prevent external-to-external call transfers.

Route filters restrict certain types of calls from going out specific gateways or route patterns but do not directly control the transfer capability between two external parties.

The Cisco Unified Communications Manager (CUCM) has a specific service parameter called 'Allow Transfer to External to External' which, when set to 'False', prevents users from transferring a call received from an external (off-net) party to another external (off-net) party, directly addressing the toll fraud concern.

Enforcing ad-hoc conference restrictions limits who can initiate or participate in ad-hoc conferences, but it does not address the specific scenario of preventing off-net to off-net call transfers.