Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the Callsign with an Area of tamworth and frequency of 0 88.9?

### Inputs:
table_name: table, columns: ['Callsign', 'Area served', 'Frequency', 'Band', 'On-air ID', 'Purpose']

### Response:
SELECT Callsign FROM table WHERE Area served = tamworth AND Frequency = 0 88.9