Cormac McQuillan (45), of Glenariff Crescent in Ballymena, denied the charge and represented himself at court during the contested hearing.
He told Antrim Magistrates' Court, sitting in Ballymena, he denied using a phone and said he had been driving home around 11pm on May 7 this year and was leaning his head on his hand because he was tired.
The court heard a police officer said in a statement she was in the passenger seat of a PSNI vehicle which was waiting to turn out of a junction in Ballymena when she saw a vehicle go past on the major road and the driver was "holding his mobile phone in his right hand with it pressed against his ear".
The officer said the area was "fully illuminated with street lighting" and the accused "appeared to be speaking, as his mouth was moving".
Police spoke to Mr McQuillan a short distance away and when cautioned he replied: "You've no evidence".
The accused cross-examined the police officer and said he had been resting his head on his hand whilst driving.
He told the court: "My car is automatic and I was just cruising on the way home. I was tired".
The officer said she "believed" Mr McQuillan had been holding his mobile phone. "I saw what appeared to be a mobile phone," she told the court.
Mr McQuillan said he had no mobile phone with him and instead it was in his home.
He asked the officer if they had searched for a mobile phone and the officer said: "That is not something we would do when we are stopping for a mobile phone".
Mr McQuillan responded: "Why not? You are accusing me. My phone was in the house so why didn't you search for my phone?"
The officer said the evidence was "two police officer statements and observations". She told the judge that when speaking to Mr McQuillan through the open window of his car she had not asked to see his phone.
The officer said Mr McQuillan replied that he wasn't on his phone.
Mr McQuillan interjected in court to say he also said the officer had "no evidence" and he said the reason for saying that was "because I had no phone".
There were no other prosecution witnesses.
In response to a prosecutor, Mr McQuillan told the court it was "not my job" to tell police his phone was at home. He said the officer was "clearly mistaken" in claiming he had been on his phone.
In giving his ruling, the judge said it would have been dark and the street was illuminated and the officer said the accused "appeared" to be using a mobile phone.
When spoken to by police the judge said Mr McQuillan denied the offence and said "You have no evidence".
The judge said Mr McQuillan's account to the court was that his phone was not in the vehicle and was at home "but he accepts that he didn't provide that account to the police".
Judge Broderick said the officer would only have had Mr McQuillan under her view "for a number of seconds".
He said Mr McQuillan's account was that he was "leaning his head on his hand" and that the accused said that might explain why the officer was "mistaken".
The judge said he had to weigh up the officer's evidence and Mr McQuillan's evidence and said there were "no other witnesses involved in the case".
Judge Broderick said legal guidelines ask courts to remind themselves "that an honest witness can be mistaken".
He added: "I think in all the circumstances, I think the officer gave what I thought was very straightforward evidence, equally Mr McQuillan gave straightforward evidence.
"I wasn't particularly impressed with his reluctance to explain to the police officer that his mobile phone wasn't on his person or in his vehicle. Had he done so, then I would have thought there were reasonable grounds for the officer to conduct a search. But given the fact that he didn't say that nor make that case at the scene then there were no grounds for such a search.
"But given the time of night the fact that the officer's evidence was that he appeared to have a mobile phone and given the fact that it essentially one officer's word against the defendant's, in my view the officer has made an honest mistake and I can't be satisfied beyond a reasonable doubt that the defendant was using his phone."
The judge said the standard of proof in a criminal case is proof beyond a reasonable doubt and given the circumstances of this case I can't be so satisfied, so on that basis I am going to mark the matter dismissed".