caller

Short definition from Wiktionary

Noun

1. 1
   The person who makes a telephone call.
2. 2
   A visitor.
3. 3
   The person who stands at the front of the hall and announces the numbers.
4. 4
   A function that calls another (the callee).
5. 5
   A whistle or similar item used to call foxes.
6. 6
   The person who directs dancers in certain dances, such as American line dances and square dances.