How do I store my text messages to go into my phone instead of my SIM card?

I have the Samsung Gravity, and I want to change the setting so that my text messages can go into my phone instead of my SIM card.How do I store my text messages to go into my phone instead of my SIM card?
opne up the text, go to options.then trasfer to phone?How do I store my text messages to go into my phone instead of my SIM card?
In my opinion, better not restore it to the phone memory because the phone memory is quite small and most of the software installed in the phone memory. So the messages (MMS, SMS) %26amp; tel.nos. is automatically go to the sim card memory.