Optatel

If you change your mobile phone often and are purchasing a high end mobile phone, it is advisable  to select a mobile phone which offers a good resale value. The resale value depends on the cellular technology used in the phone and whether the phone is locked or unlocked. Unlocked phones can be used with any mobile service provider using the same cellular technology.

In general, GSM mobile phones which are maintained well, can can be sold for a good price even when they are used. Unlocked phones also sell at a relatively higher price.

The most popular brands in terms of resale value are:
Nokia
Sony Ericsson
Palm
TMobile Sidekick[s]

Mobile phones, mobile phone services