Once you sync with the telephoneNumber in LDAP, then you have login with the telephone number User ID for both EM and ccmuser.

The "LDAP Attribute for User ID" is used to select which AD user attribute is to be set as the user ID in the CallManager.

sAMAccountName -> 'User Logon Name' under the Account attribute for the user

telephoneNumber -> 'Telephone number' under the General attribute for the user

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If the LDAP userID attribute is changed from sAMAccountName to telephoneNumber, this would then force user IDs to be synced to the telephone numbers. Hence, users will authenticate/login to EM and ccmuser with their phone number.

It can be chosen whether the 'Phone Number' in UCM (LDAP - > Directory) maps to TelephoneNumber or ipPhone in AD.

telephoneNumber -> 'Telephone number' under the General attribute for the user ipPhone -> 'IP phone' under the Telephones attribute for the user

If currently using the ipPhone field in synchronization with LDAP/AD, then the telphone number in the user page will display the corresponding ipPhone value. For example :

First name : Cisco

Last name : Tac

Telephone number : 1000

IP Phone : 2000

LDAP synced with 'telephoneNumber' (under LDAP -> System), and 'Phone Number' synced to value 'ipPhone'. This will result in

User ID : 1000

First name of User : Cisco

Last name of User : Tac

Telephone number of the User : 2000

However, the user ID is the same, whether to login to EM or use the ccmuser page. So once you sync with the telephoneNumber in LDAP, then you have login with the telephone number User ID for both EM and ccmuser.