Does the iPhone 5S struggle in high signal areas? I have just been sitting in a car park, next to a high rise building with what I suspect to be the network I use mast, using 3G. I have the dB enabled on the iPhone, and it was registering -61dB at one point, and I couldn't make calls too well, with either the audio cutting out, or call failed showing up on the display. Internet too was stuttering and slow overall. I've just moved down the road, and everything is fine now. I was surprised to see this problem, as my wife and her iPhone 4s had no problems.