I have a 1.1.1 unlocked iphone and have been experiencing problems while sending sms. I have done various tests and have discovered the following. I am able to send messages to any contact when I am sending a message to that contact for the first time or whenever that contact has not sent me an sms. I am able to receive all messages. When a contact sends me an sms, I am no longer able to send that particular contact an sms. But if I delete the conversation, I am able to send that contact messages again. Does anyone have any clues on what could be happening? Is anyone else experiencing this problem with their unlocked phones? A friend of mine has the same iphone and unlocked it using simfree (as I did) and does not have this problem. I appreciate any help that can be provided. Thank you.