The settings:PhoneNumber element ([MS-ASCMD] section 188.8.131.52) is an optional child element of the settings:Set element in the Settings command request. It specifies the telephone number that identifies the mobile device.
The telephone number facilitates troubleshooting and device management by providing a well-known, unique identifier for the device. The value of the settings:PhoneNumber element can be up to 1024 characters in length. The server does not validate the value of the settings:PhoneNumber element.<1>