I don't believe they have made that a law yet. In 2010, they were considering making a law that prohibits driving a vehicle while talking, texting, or typing on a mobile communication device, and it would count as a secondary traffic offense. However, I don't believe that bill has been passed.
Ohio doesn't have a state-wide law on this, as a matter of fact, the municipalities are able to create their own laws regarding cellphone use while driving. I'd advise you to call your local police station and ask them directly if this law is in effect where you are.