There is only one Telephone number field under End User configuration, so I think there can be only one number per person. It also makes sense, because when you try to dial someone through the phone it has only one phone number to dial as well.

You can choose either the "Telephone number" or "ipphone" AD fields of an LDAP user to be the ones imported to CallManager under - system - LDAP - LDAP directory.

:JoeL