Hey everyone. First of all, I apologize if this is not the right place to post this, but I've been working on it for days now, and I'm getting desperate. I have an iPhone 4S that is locked to Softbank. iOS version is 7.0.2. I'm trying to use a GPP interposer from China3GPP to get it to work with a T-Mobile prepaid SIM. It is advertised as working with iOS 7, and I heard a lot of positive feedback from Japanese people in the same position as me. The interposer allows me to access the phone as if it was unlocked, but my T-Mobile SIM displays "No Service" most of the time. Occasionally, if I remove and reinsert it, it will display T-Mobile, and cycle through "No Service" > zero bars > one bar, repeat loop. My number is displayed as "Unknown," and I am unable to use the phone to make calls or send texts. Inserting my friend's Verizon SIM into the Phone resulted in "No SIM" where the carrier would normally appear at the top of the Phone, but the iPhone recognized the phone number from the SIM Card, and a new 3G option appeared under Settings > Cellular. My T-Mobile SIM did not provide service on his Verizon Lumia 520. I've tried setting it up with both epc.tmobile.com, and fast.t-mobile.com APN settings. Manually choosing T-Mobile or T-Mobile (3G) as the carrier does not resolve the problem. I've tried formatting the phone, and done the GPP unlock process multiple times. I'm completely out of ideas, and I'm getting really bummed . I'd really appreciate any advice.