Purchased a Samsung S4 phone in the U.S. Unlocked. Can't get internet with Israel sim. What could the problem be?

[AC Question]

Purchased a Samsung s 4 phone in the U.S. Unlocked. Can't get internet with Israel sim

Hello. I recently purchased an s-4 unlocked samsung unlocked and purchased a plan through the "Hot" network. The phone works fine however I can't access the Carriers internet using the phone. I can however use it at hot spots. What's up? Thanks.