Call on my cell in Costa Rica

I paid for an international plan so I could visit Costa Rica and use my cell phone to call within the country using the area code +506. But I have not been able to call any numbers while in the country - the phone keeps telling me the calling is restricted.  How to fix this?? Do I need to put a 0 in front of the + before I call???? I need to make calls!!  Can anyone help?   I get text messages with no problem.