How to choose

Which voice agent setup? Five questions

1. Inbound or outbound? Outbound brings TCPA consent, caller-ID labels and disclosure, which decide whether a campaign is viable at all. The TCPA doesn't treat inbound calls as "made" by the business, so inbound comes down to whether the agent resolves calls well enough, plus recording notices and disclosure.
2. What does a wrong answer cost? If the agent quotes prices, refunds or policy, the business is bound by what it says. Use a stack that can check the text before it's spoken, and read back anything the caller must get right.
3. What data does it touch? Card numbers should go to keypad entry with masking or a secure link so the model never hears them; health data needs a business associate agreement (BAA) with every vendor in the chain; voiceprints bring biometric law. Each narrows which vendors and models you can use.
4. How long are the calls? Long calls raise speech-to-speech costs unless caching holds, Google's Live API drops connections after about 10 minutes and has to resume them, and Vapi's default maximum call length is 600 seconds.
5. Who pays when it fails? On per-minute pricing you pay for a failed six-minute call and then for the human minutes after it. On per-resolution pricing the vendor carries that, and the argument moves to what counts as resolved.

My defaults: for an inbound line like the payroll company's, I'd have the agent answer every call, verify the caller and handle the few most common requests, with a warm transfer for everything else and for any change to bank details. I'd say "AI assistant" in the greeting, announce recording and name the vendor that handles the audio, and keep card numbers on the keypad. I'd measure containment and resolution separately, with a person checking a sample of transcripts each week, and widen the agent's scope only once resolution holds. For outbound, I wouldn't dial without consent records I'd be happy to show a court.