Identifier-sharing methods for wireless communication devices are proposed along with wireless communication devices and base stations using the same method. The proposed methods allow multiple M2M devices to share the same device identifier. The shared device identifier is valid for only one M2M device in a given time interval by a mechanism of assigning the same periodicity value and different offset values to the M2M devices associated with the shared device identifier. The proposed methods can also categorize M2M devices into different classes respectively based on their M2M application types. By adjusting periodicity value associated with the shared device identifier, a class associated with delay-tolerable applications can be allocated with more M2M devices sharing the same device identifier in comparison to the another class associated with delay-sensitive applications.