Question: When both a Mobile Equipment (ME) and a 3GPP UICC application support both the 3G Phone Book and the Contact Manager, which entity should be utilized for managing contacts?
Option 1: Always use the 3G Phone Book as it is universally supported.
Option 2: The choice between the 3G Phone Book and the Contact Manager should be left to the end-user's preference.
Option 3: The Contact Manager should be used, as per the defined external interface for such scenarios.
Option 4: Both the 3G Phone Book and the Contact Manager should be used simultaneously for redundancy.
Explanation: Utilizing the Contact Manager is the recommended approach when both options are available on both the ME and the UICC application, ensuring consistency and leveraging potentially more advanced features for an enhanced user experience and functionality in telecom networks.