NEC e616 questions
 

Hello, I have a NEC e616. I think it's from UK and used to be locked to Three network. It is unlocked and works well but I want to do a factory reset. Does anyone know if the phone will remain unlocked after a factory reset? Or will it have to be unlocked again?

Also, I am having problems with GPRS. It keeps appearing and disappearing randomly. If I am fast enough to start a download or start loading a page the connection never disappears. A symbol similar to this = appears when GPRS is available and becomes green = when a download takes place, but after it's done it always goes away. This phone probably did not have a factory reset in 10 years so I think maybe the reset would help?

I know this phone supports UMTS 3G but my SIM is old and does not let me choose 3G. The strange thing is my SIM does work with newer HSPA 3G in an Android. Anyway I want to try getting GPRS to work before buying a new SIM.

I bought a new SIM of the same operator and 3G does work and internet availability is better but it still tends to disappear. However it's even worse than the old SIM because the phone keeps crashing or restarting, not sure what is happening. Maybe there is a bug or some memory leak. Maybe a factory reset would help but I am afraid a factory reset will lock the phone to it's original carrier. Or maybe the GSM/3G module is damaged or some other hardware.