reset old iphone

[finketr]

i have a new phone and my old phone.

my new phone is all set.

i'd like to reset my iphone 3gs so i can use it separately and essentially as an ipod... anyone got any hints on how to do this without erasing my old phone?

thanks

[FBPro]

I never had a 3 but my guess would be go into settings then general then somewhere is probably reset and just reset all settings but NOT erase data.