We've figured out was causing the issue and now have a fix available for the SMS and MMS issue for iOS 5.1.1 for the GSM iPhone 4S.
Some GEVEY™ Ultra S users noticed that their GSM iPhone 4S was changing the SMS and MMS settings back to the original carrier settings after reboot. This issue was found to be an unannounced change in iOS 5.1.1 that would trigger this reset.
Apple N Berry, LLC has found a solution to this issue. Due to the numerous counterfeit GEVEY™ products flooding the market, we won't be publishing the solution online. Please contact support and we'll be happy to help GSM iPhone 4S customers who have issues with SMS and MMS setting using GEVEY™ Ultra S. Have your order number and e-mail address ready when calling support.