How can I stop iPhone fom syncing call history and total call time from old phone?

I have set up the phone as a new phone, and deleted icloud backups. I have deleted local backups as well, and given the phone a new name. Directly after wiping phone, it is fine and reports no call time, but after a day or so, all the old calls and total call time resyncs from my old phone. I have not restored any backup to it, so am not sure where this is coming from. I don't want this to happen, but can't figure out how to stop it...