The extra time it takes to transmit your move to ICC and your opponent's move back to you is known as lag. Lag affects all iPhone games to varying degrees, and signal strength affects the amount of lag you experience. If you have less than full bars, you can expect to have more lag. With that in mind, you can offset lag by picking a time control that compensates you for lag by selecting a larger time control and larger increment (seconds returned to your clock after you move). Trying to play fast games when you are experiencing lag will often result in a time loss.