It is correct and fine to say "disturbance on your side" in a telephone conversation.
"Disturbance on your side" means exactly what it sounds like it means, therefore it is not an idiom. It expicitly refers to a disturbance, which is on the other end of the communication line relative to the speaker.
An idiom is a phrase which either assigns a meaning to some instance of bad grammar ("catch as catch can"), or an understood meaning which is quite different from and cannot be deduced fromn the literal meaning ("kick the bucket").
Colloquially, people use "idiom" when they mean "oft-used phrase" or "canned phrase associated with a situation"; but strictly speaking, these are different concepts. Not all idioms are often used, and not all often used or canned phrases are idioms: only when their meaning is other than the literal one.
There isn't any special, often used, or preferred/expected way to express the idea "disturbance on your side", so you can be as creative as you like.