The dialplan-pattern command have two functions
For inbound call, creates a second dial peer with the full E.164 number to match the same ephone
For outbound call, convert the calling ephone extension into full E.164 numbers
<note warning>This command can be problematic and can cause problems when integrating with CUE as described below</note>
When pressing the message button, CUE is presented with the Full E.164 number instead of the phone extension causing CUE not to recognize the calling party and prompt for the ID.
When call forwarding to voicemail extension and the voicemail extension is in the same range as the dialplan-pattern, the forwarded voicemail pilot number will be expanded to the full E.164 number and result in a reorder tone. Even though calling the voicemail pilot extension directly or through the message button works.
<note>The last problem is actually a known bug with Cisco bug ID CSCee57422 </note>
Outbound call from CCME
Inbound call into CCME
telephony-service
dialplan-pattern 1 2095559.... extension-length 4
voice register global
dialplan-pattern 1 2095559.... extension-length 4
telephony-service
dialplan-pattern 1 209555944.. extension-length 4 extension-pattern 50..
voice register global
dialplan-pattern 1 209555944.. extension-length 4 extension-pattern 50..