First...if you don't have caller ID I'd *69 to see if you could retrace the number...I get a lot of calls from GOP organzations, GOP-PAC, etc, and they go through a three minute speel before asking if I'll contribute and never ask for a card number up front...the giveaway that this is a fraud was the "it won't hit till the end of the month" bit.
I do have caller ID and it was an 800 number.