(using a phone as a modem gsm).Avoiding the problems of delays,AT gramathic having a lucky of using textmode,I waiting a string of only 4 numbers,but I receive also of course a lot information as sender number,time,..the "okeys"back from the phone etc.I hear that this is a question of strings conversions.I can not just compare the response with a previous stored response because after a string 4 numbers are received I need to decode those numbers(converting to integer) and read each and every one of them independent(I can not compare 9999 "posibles commands") -how can I extract those 4 numbers(the only text)and avoid all the other unpleasent data that is coming on uart maybe you have few examples,recomended functions or something else