It depends if you save your contacts into your cell phone or into the sim card. Boost Mobile uses sim cards like A T&T and T-Mobile however Boost Mobile uses a different network called IDEN and not GSM like A T&T and T-Mobile. Basically each IDEN network cell phone on Boost Mobile has a walkie talkie feature and uses a sim card. You can save your contacts onto a sim card and use any other Boost cell phone and your contacts will show up. However if you took your sim card out and got another sim card and put into your cell phone then your contacts will probably not show up.
Boost Mobile also uses another network called CDMA network. This is the sprint version network and so their cell phones don't have the walkie talkie feature and don't use sim cards.
