How do I import all contacts from a SIM-card to an Android phone?

My mother have got a HTC Wildfire with Android 2.2. Now I want to import all contacts from her old SIM-card to the phone. I did it and it worked. Then I switched to the new SIM-card, and now when I start the phone, the contacts has disappeared. How can I import the contacts from the old SIM-card to the Android phone? This is a really annoying problem.