A780 resetting every time i make a call

[laseru]

hello everyone!
this is the first time i post on this forum, i'm not a native english speaker so please forgive my mistakes.

a friend of mine has a motorola 1780 but everytime he tries to call someone the phone is restarting. the same thing is happening when he receives a call.

he can browse the menu, listen to music , watch videos but he cannot make calls.

i need to know if this is a software problem or the problem is hardware.
if it is a software problem this can be resolved with a firmware upgrade?

[homewayma]

I think it's a hardware problem.The current when you make a phone call is much larger then you browse the menu, listen to music , watch videos.
so:
1.Try to use another battery.
2.Mainboard fix is needed.

[swifty]

just another guess,
have you tried to replace the sim card?