Mobile Phone has been widely used in the world and adopted in different application areas involved with SMS. SMS has been evolved for downloading logo, ring-tones, advertisement, security notes, and location based system. This paper describes an extension to current functionalities of SMS. "SMS Credit" is a prototype, which allows customers to perform electronic payment using their mobile phones via SMS without the need to modify existing devices or to acquire new equipment. Users simply send SMS to connect to the background GSM system and key-in the charged amount, their account will then be automatically credited once the transaction is authorized. Specific wireless terminal is installed at participating merchants and service providers, which allow customers to identify and authorize a transaction. Example scenarios on actual application on telecommunication and electronic commerce field will be discussed.