A company identifies a fraudulent toil situation. An engineer reviews the Cisco UCM call detail records and discovers that fraudulent calls originate from a Cisco Expressway-C server and are then…

Question

Options

• Acalling search space that contains all the partitions on the Unified Communications Manager SIP
• Bcall policy rule from the DNS zone to allow a destination regex pattern of \d.*@abc.com
• Cunique search rule with a regex pattern of [5]\d{4}@abc.com that targets the neighbor zone
• Dcall policy rule from the DNS zone to allow a destination regex pattern of .*@abc.com

• A
  80% (24)
• B
  3% (1)
• C
  3% (1)
• D
  13% (4)

Explanation

To prevent toll fraud and restrict what calls Cisco UCM will accept from Expressway, the control must be enforced on Cisco UCM, not on Expressway search or call policy rules. By configuring a Calling Search Space (CSS) on the UCM SIP trunk from Expressway that includes only the partition containing internal extensions (5XXXX), UCM will reject any calls from Expressway attempting to reach PSTN or other unauthorized destinations. This is the correct and recommended method to limit inbound Expressway calls to a specific internal extension range and stop fraudulent PSTN routing.

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