44 in bb

[BK123]

6 handed party 5/10
63/6/2 utg limps, unknown utg+1 limps, sb completes, hero checks 44 in bb.
6d 9d 3c flop, checked around
2s on turn, sb checks, hero bets, utg raises, folded to hero...?

[jph0424]

I think I call down because this raise is very suspicious. If he really had a strong hand he would probably call to encourage more players and raise you on the river.

[Wes ManTooth]

This may be more read dependant, you said he was unknown so you may want to call this down though I think you are behind on this one.