Does the Samsung Eternity use a Sim card?

"Yes. All phones need a SIM card, or it will not function." Actually, that answer is incredibly wrong. SOME phones use SIM cards. Some phones don't. A phone on the Verizon, Alltel, or Sprint networks do not use SIM cards as they operate on CDMA platforms. iDEN (an ancient Nextel system) or the global standard GSM (AT&T) use SIM cards.