Transfer new contacts to sim on 3gs

[Dennis iPhone]

As I understand any new contacts you may wish to save. It can only be saved into the phone memory & not the SIM card. Unlike other phones whereby you have an option to save in phone memory, SIM card or both.
My question is, how do you transfer whatever new contacts you have saved in the phone memory to the SIM card? Thank you.

[iNinja]

You cant - you have to sync them to google or where ever and then you have your backup