"On the phone, his voice was full of tears and emotion."
Translation:Au téléphone, sa voix était pleine de larmes et d'émotion.
I would think so. It is hard to be definitive as French has almost as many regional variants as English. but "sur le téléphone" does sound very off used that way.
In any case it i much safer as a first approach to stick with "He's on the phone" = "il est au téléphone"
(Also, it is spelled "anglicisme" in French)