Unlocked 5C iPhone in Japan works on home wifi but won't connect to Public Access sites.

Unlocked 5C iPhone in Japan works on home wifi but won't connect to Public Access sites. Phone was a BELL Canada phone and has Sim from Japan for Data in it. Imessage isn't working unless at the apartment? Please help I can't afford to buy a new iphone here?

I have reset networks and iMessage works fine in my apartment. SMS works with my Sim but I can't use iMessage away from the house.

I have done everything but take it into a shop and ya my Japanese isn't going to allow for that to happen or I will end up with a new phone.

Help me please...