I been wondering if i could use those "unlocked" cellphones that are widely sold in eBay with metro PCS and why metro pcs phones dont have a sim card? i have never really understand the sim card concept and if you can actually find a "unlocked" sim card as well. so i just need to know, can i used those phones with metro pcs? i just dont like the crapy phones that metro pcs has to offer and not to mention the prices. help please!