I already tried imei.info and it doesn't work. So I bought my iPhone from a third party store and I don't know if it's unlocked. The person that sold the phone to the store had AT&T before. My phone is on Net10 right now and I have data, talking, and texting with them but I am unable to MMS anyone who does not have an iPhone and I was told that is because my iPhone needs to be jailbroken, because I have iOS 6.1.3. The reason I want to know if my iPhone is unlocked is because I want to switch from Net10 to T-Mobile and when I called customer service they told me they will not sell SIM cards to consumers who don't have unlocked iPhones.