Even if you have jailbroken your iPhone, the device must be free from network restriction to use with any other network. If it is network restricted, you need to unlock it. You can unlock an iPhone safer and easier using remote unlocking service. You can get the remote unlocking service for an iPhone from SimpleUnlocking.com This method of unlocking is safe, simple, affordable, quick and permanent. IT doesn't require a jailbreak too. Good luck.