Pda Unlocked

If a cell phone or PDA is unlocked I can use my wireless service plan existing on that?
I'm considering buying a new "BlackBerry 7290 Unlocked GSM line. He said it was unlocked, does not require activation. Since I 'm a Sprint PCS service plan wireless cellular phone, etc. .. Will I be able to activate my service available in the default, if I buy it? Thank you!
You have Sprint. It is a CDMA service. A GSM phone is not working on it. They are different technologies. Do not buy it.
UNLOCKED A88 PDA 3.2″LCD TOUCHSCREEN PHONE DUAL SIM