Get transfer_to_phone tool configuration

Retrieve configuration for the transfer_to_phone tool.

This tool transfers calls to specific phone numbers. Configuration includes:
- List of phone destinations (each with phone number, name, availability hours)
- Transfer message (what the agent says before transferring)

Note: This tool is mutually exclusive with transfer_to_mobile_operator.
Only one can be enabled at a time.

The agent must belong to your organization.

Authentication:
- API key with READ or READ_WRITE permission