I need help!!!

I am wanting to buy the Siemens SL55 mobile. i am wanting to buy it sim free. I am wanting to put the sim card from my old phon in it but not sure if it will fit. my old phone is a Sharp GX-10i. can you help me? Jay

I need help!!!

I am wanting to buy the Siemens SL55 mobile. i am wanting to buy it sim free. I am wanting to put the sim card from my old phon in it but not sure if it will fit. my old phone is a Sharp GX-10i. can you help me? Jay