How can you tell if your iphone is jailbroken or not?

Question

How can you tell if your iphone is jailbroken or not?

Answer 1

it is jailbroken if you can use it with other sim cards than the one it is locked to..

for example if you have an AT&T iphone and you put an T MOBILE sim card in and it works... congrats its jailbroken

Answer 2

Well i forgot if jailbreaking is for tmobile or to get custom apps but to test it you can see if you can put a sim card in and try it out. and for the custom apps you should see something called installer or cydia.