So I found an iPhone and I unlocked it already, which was step 1.
The day I unlocked it, everything seemed to work perfect, but that
night, the SMS and Phone did not dial anymore. Once I dialed the number and
pressed call, an operator would say"we are unable to make calls from this line." what does that mean?
this phone still has the same SIM card, so what I'm thinking is that the person froze/cancelled the account? is it true?

everything else is working perfect though.

need info fast, please, thanks!!!

hmm... I suggest u download iliberty+ on win or ilibertyX for mac and downgrade your BL to 3.9FB if necessary. Next, download ziphone and use the "erase bl3.9 baseband" function. Then restore to 1.1.4 with iTunes and rejailbreak/activate/unlock with iliberty. If that doesn't work I'd say its your carrier.

Hope this helps its real scary when something like this happens. I've been there before

I'm having the same problem, for me all was working fine and then the dailer would say called failed once the call was sent, latter the network (O2) said no service, I changed sim to a different notwork (meteor) but still no service, funny thing is a friends vodafone sim works fine, All O2 and Meteor sim appear to be banned. I tryed the above fix and umpteen relocks unlocks but nothing works.

i have done what you havea told me to do, so i am guessing it is my carrier. the sim card is with at&t and has signal, so it still has the same message when i try to call somebody.

i also wanted to know how i can change carriers and how to do it. thanks!