Signal Strength The phone was working fine until about a week ago. Then started to notice complete lack of signal strength. Tried a different sim from different carrier with the same result. Sometimes depending on the location, the phone shows full signal, however as soon as a phone call is attempted signal just drops to nothing dropping the call.

You may also discover that the machine's internal memory is full or you have a very large number or programs open. This can be a cause of stuttering calls. Try a soft reset or the slightly more complex hard reset. Look at the O2 website for a ROM update (that will possibly improve the phone's "Radio" stack i.e the program that processes the phone signal). If you are feeling brave you could upgrade your phone rom after reading all the relevant details on XDAdevelopers site http://wiki.xda-developers.com/

This problem usually happens when you drop the phone and the antenna gets out of her place, then it's only has signal in near the operator antenna, I suggest you take it to a professional who will look at it.shouldn't cost too much