YE this is the problem for all Samsung Slim, Its nothing its only a problem of a MIN no which is generated during the activation of a number. I your case your mobile has not saved the new gnerated MIN Number. If u want to know your MIN NO. just go to the Nearest Service center. OR if u have the MIn Writer of samsung slim then post your RSN and UR MOBILE No on that RSN, then i will give your new MIn number