If the police have made an error in the information they have submitted to the court then it would be worth pointing this out to the court ASAP - with a suggestion that a procedural impropriety has occurred.
If I were a judge, or a lawyer (and I'm neither) then unless you have persuaded your phone company to provide the incoming call records for the date in question then the chances of you being able to win a case like this are small. You may well be able to prove that you hadn't placed a call, but the counter argument will be that you received a call rather than placed one.
If you get stopped for using a mobile phone then if the police have made a mistake IMO its better to sort it out at the time. Of course they are used to people arguing the toss. Be polite - show them the phone, where it was in the vehicle, what the time is set to and the incoming and outgoing call logs. If they say that you could have deleted the offending record then show them how that is done on your phone and point out that from the time when they signalled you to pull over to when you stopped you would not have had time to delete the record. Above all, stay calm. Do not argue with them, if they give you a ticket then take it but maintain that you are innocent.
If the police haven't made a mistake, just admit your guilt, take the ticket and learn the lesson.
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