If you're planning to change mobile companies, don't forget that in a short period of time your old phone is going to stop working. (If the phone is unlocked, then obviously you'll have no problems.)
MobTime Cell Phone Manager is an excellent app that let's you back up the info that you've stored on your phone: your contacts, calendar, text messages, images, videos, etc.
The app supports dozens of makes and models of mobile phones, including: Nokia, Motorola, SonyEricsson, Sharp, Siemens, LG, Panasonic, etc.
MobTime Cell Phone Manager can be connected to your phone in three different ways: via USB or RS232 cable, an infrared connection, or BlueTooth.
Some functions are disabled and the name of the program's developer is added to your text messages.