iPhone 3GS drops call and reverts to apple logo
Fully charged iPhone 3GS with masses of free capacity drops calls after a few minutes chatting and reverts to apple logo. I am not sure if is rebooting but seems to come back to life a couple of minutes later. It has done this for months if not years and across several firmware versions. It may very well have done it from new. Is there an internal log that I can get at to see what is happening ? Carrier will blame phone and Apple will likely blame carrier. Someone help please. It's been a great phone otherwise. Note have not upraded to iOS6 because of crappy mapping. Google Maps is one of my most used apps.
Regards
MacBook Pro, Mac OS X (10.6.8), 17"