But why stop the blocking there? You can block your number from showing up on the other person's caller ID in the off chance you're dialing an ex-lover or making a crank phone call. Not that we're suggesting anything...
Enter #31# before you dial the number and your number will come up as "No Caller ID."
You can also use iPhone codes to figure out how strong your phone signal is. The signal bars in the top left-hand corner actually aren't all that great. To find out precisely how much signal you have, you'll have to enter the super-secret field test mode. Shh!!
Instead of bars, you'll see a more accurate form of measuring your signal strength. The closer the number is to -40, the better your signal is. Anything above -80 is a pretty good signal. If the number is at -140, your signal is terrible because you actually have no signal at all.