All users report that when they press the Messages button on their IP phone, nothing happens.
What is the most likely cause of this issue?

A.
Cisco Unity Connection is not configured.

B.
The default Voicemail Profile does not have a Pilot number configured.

C.
The Voicemail Pilot does not have the VoiceMail Profile configured.

D.
The Integrated Service Engine is offline.

E.
The Voicemail Pilot is incorrect.

Explanation:
The voice-mail pilot number specifies the directory number that you dial to access
your voice messages. Cisco Unified Communications Manager automatically dials the voicemessaging number when you press the messages button on your phone. Each voice-mail pilot
number can belong to a different voice-messaging system
Link:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/6_0_1/ccmsys/a06vmccm.html#wp
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