Need to switch old sprint Gal 3 to straight talk. Not sure which activation card to buy. BYOP or the( NANCA ) not sure if usin

Solution
BYOP is bring your own phone, NANO is the size of the card, they are not an either/or thing.

Contact Straight Talk or check their bring your own phone web site, that will tell you.

If the "Gal 3" is the Galaxy S3, it has a micro SIM.