http://www.T-Mobile.com/shop/Phones/Prepaid.aspx --- (purposely not linked to ensure going through a Cash Back site)
Nokia 2610 (prepaid - no contract)
go through FW, DK or ER & get your $5 Cash Back!
good as a back up phone. great if you're gonna buy a $25 card anyways. it might even come with the original $10 air time card to activate.
Remember to activate the SIM to get your Cash Back!

