The Certkiller administrator configured analog DTMF integration between Cisco CME and legacy VM. However, he noticed that unanswered calls from extension to extension are forwarded to VM, but unanswered calls from PSTN are not forwarded to VM. What did the administrator neglect to configure that is causing the problem?

A.
Pattern trunk-to-ext busy.

B.
Pattern ext-to-ext busy.

C.
Pattern ext-to-ext no-answer.

D.
Pattern trunk-to-ext no-answer.