I received an S2 as a gift in October, used it without issue until early January. I'm on a PAYG plan with RedPocket on AT&T's network. I've tried in vain working with their CS team for 3 weeks but have gotten nowhere (sidebar: Red Pocket customer service is horrible, never ever use it or this company ). I am unable to send/receive phone calls or texts, though I can access voicemail by calling from my landline. When I try and dial out or send a message from my S2, I get the messages "Not Found on Network" or "Mobile Network Not Available". I've heard this is an issue with S2, but what can I do to resolve it? This phone was unlocked--would a factory reset have locked it? Red Pocket said they confirmed with AT&T that I am not blacklisted and should be able to use their network. I tried removing/reinserting the SIM; checking my IMEI status online (says it shouldn't be blacklisted); using a new SIM card (didnt work in my phone, worked fine in another); did a factory reset and had the same results. Red Pocket said they could not provide me the phone settings, AT&T told me I need to get them from Red Pocket. What other steps can I try to get my phone to work, short of trading this in, sucking up the extra $ for a slightly less expensive PAYG plan and possibly using T-Mobile? Thank you for any suggestions or help you can give! If I need to clarify or give more information, please let me know--I'm desperate for help!