Help....Baseband Problem Here topic

Nealry I Helped My Friend S3 To Flash Stock ROM....After Flash I Found Out That The Baseband Still Same Like Last Stock ROM....XXLLEE...I Flash Other Baseband Stock ROM..Wont Change It...Any Solution:confused: And That The Cause Of Making My Friend Phone Wont Get Any SIgnal...Always Show Not Registered On Network Error...If Any Solution I Really Appreciate :D