The C139 is the cheapest model in Tracfone's lineup.  It's a very good basic phone that gives you good voice clarity and easy text messaging.  Because Tracfone doesn't have a lot of services to offer (which isn't a bad thing for people who only want basic cellular service), this phone doesn't give you music downloads or live TV (which on other carriers are mostly misleading hype anyway).  The color screen is small but good-quality.  The only thing I don't like is Tracfone's 60-day refill polic: you must refill every 60 days to keep your account active; otherwise you forfeit your number and balance.  Other prepaid providers like Speak Out Wireless (from 7-Eleven) give you one full year of usage.