Dial Plan Considerations

Cisco UE deployed with Cisco CME requires that the IP phones that have mailboxes all have extensions of the same length. The specific length of the extension does not matter: the length of the extensions can be anywhere between one and 16 digits (as supported by Cisco CME). What is important is that all extensions with mailboxes must be of the same length on a particular Cisco CME and Cisco UE system.

Chapter 7 covered various ways in which you can manipulate digits on dialed numbers to translate PSTN numbers (E.164 numbers) into local extensions:

• Cisco IOS dial peer commands
• Cisco IOS translation rules
• Cisco CME dial plan pattern commands

Another way to configure the mapping from PSTN numbers to internal extensions is by using the E.164 number configuration of Cisco CME and Cisco UE. These fields essentially associate a second numberthe fully qualified E.164 numberwith the extension or mailbox so that dialing either number terminates on the correct extension or mailbox.

Cisco CME has a Secondary Number field, as shown in Example 10-10. You can access this same field by using the GUI by navigating to the Configure > Extensions screen. Filling in the Secondary Number field on that screen associates an additional number with the extension so that calls dialing the extension directly (likely other IP phones) and calls dialing the DID number (likely PSTN callers) terminate on the phone without further dialing plan assistance.

Example 10-10. Cisco CME Secondary Number Field

Router#show running-config ephone-dn 1 number 6001 secondary 5103953001 description Grace Garrett name Grace Garrett call-forward busy 6800 call-forward noan 6800 timeout 10

The effect of configuring the Secondary Number field is that an E.164 PSTN number can terminate directly on an extension without digit manipulation of the called digits. If this call forwards into Cisco UE voice mail, the Called Digits field still contains the full E.164 number, which must be recognized by Cisco UE as a mailbox owner. This requires the configuration of the Cisco UE E.164 field.

Cisco UE has a Primary E.164 Number field that you can also access by navigating to the Configure > Users screen in the GUI and clicking a specific user to highlight that person's parameters. Filling in this field associates an additional number with the user (and therefore the user's mailbox) so that calls dialing this number directly can enter the mailbox for the correct user.