I've had some very poor reception in some areas in the UK where my operator's signal-strength map suggests a very good signal should be received. Sometimes just moving the phone from one desk to another at work allows it to receive a signal! I discussed this with my phone operator and they are suggesting that a new replacement SIM card may resolve the problem and are sending me a new one. When I bought my HTC Desire a few months ago I just reused the SIM from my old phone and it is a few years old. My question is this: could an old or faulty SIM card cause wild fluctuations in reception signal strength?