Apparatus and methods to support multiple subscriber identities in a wireless communication device are disclosed. A representative method includes the wireless communication device communicating with a first wireless network via a first wireless cellular protocol software stack for a first subscriber identity provided by a first subscriber identity module; communicating with a second wireless network via a second wireless cellular protocol software stack for a second subscriber identity provided by a second subscriber identity module; and sharing mobility management tasks between the first and second wireless cellular protocol software stacks when the first and second subscriber identity modules are each associated with the same wireless network provider either as a serving carrier or as a roaming carrier.