Palm Treo 700w / 700wx

hi, I am trying to use my dad's old phone as my phone. When I started this idea, I naively thought that I would be able to change out the sim card and be on my way. Well i am here now hoping for any advice on where to go now. Is there a sim card somewhere in the phone? If not, how hard is it to change carriers, I switched to verizon and sprint literally have their name written on the phone.