caller

noun

1. The person who makes a telephone call.

   “―I’ve got someone on the line. ―Who’s the caller?”

   “Thaler was arrested in Orono last May when a caller reported that the car she was driving had a shattered rear window and a blown-out tire.”

2. A visitor.

   “a gentleman caller”

3. The person who stands at the front of the hall and announces the numbers.
4. A function that calls another (the callee).

   “If the called function throws an exception, the caller should be prepared to handle the error.”

5. A whistle or similar item used to call foxes.
6. The person who directs dancers in certain dances, such as American line dances and square dances.