wie sichere ich meine iphone4-kontakte für einen Providerwechsel?

Hi,

i am an iphone4- and ipad4-user and i´m going to change my provider soon. that means i now have to save all contacts from my recent simcards (two simcards) onto the cards of the new provider. does anyone know, how to manage that as easy as possible?

i am macuser as well (macbook pro 15", mac os x 10.8.4), but not knowing, if or which software i would need for to manage the above operation.

Thanks very much for any help.

Best

Jörg Daniel