1. A method comprising: receiving a registration event notification, the registration event notification being generated by a time-based trigger, wherein the time-based trigger is activated when a first device is not used for a defined period of time; after receiving the registration even notification, sending an alert to a second device regarding the registration event notification; and routing a communication intended for the first device to an alternative device based on a classification of an originator of the communication, wherein the first device and the alternative device utilize contact addresses at which a public user identity is registered and wherein a same serving call/session control function is used and established until a last device registered with the public user identity has been de-registered from all contact addresses.