I have a jailbroken verizon iPhone 4s 6.1.2 with good ESN and is now working with pageplus. I just got this "FALWOK ULTRA S UNLOCK CDMA VERIZON 4S OS 6.1.1 6.1.2" from ebay and it is suppose to make the gsm capability of the 4s to work. I want to test the phone with the gsm sim(straight talk) that I have but after the testing and if it will work, how can I go back to pageplus(cdma)? Just remove the sim and it will automatically go back to cdma? Is it going to be the same procedure if the testing fails, just remove the sim? Please advise.