A Checklist for Choosing a Voice AI Vendor for Financial Services

Score vendors on a real phone call, not a demo

Voice AI demos run over wifi with a scripted question. Your callers are on a phone line asking about their application. This voice AI vendor checklist is built around whether a vendor holds up under those conditions, and whether it meets the compliance bar a regulated call carries.

1. Speech pipeline latency

• Is it native speech-to-speech, or a cascaded speech-to-text then LLM then text-to-speech chain?
• Ask for a measured turn-taking latency on an actual PSTN call. Cascaded stacks add up to seconds; conversation stops feeling like conversation past a few hundred milliseconds.

2. Barge-in

• Can a caller talk over the agent and be understood mid-utterance, or does it finish its sentence first?
• How does it behave with background noise on the line?

3. Actions under your rules

• Can it call your systems (application status, product eligibility) and run your rules, or only answer from an FAQ set?
• Are tool calls schema-validated so a malformed action can't execute?

4. The warm handoff

• Does escalation transfer the live call with the transcript and structured data preloaded on the human's screen, or is it a cold transfer into a fresh queue?
• Can you set hard escalation rules: anything that could constitute an adverse action goes to a human?

5. Compliance

• A recording-consent disclosure and a stored consent record, not just the disclosure playing.
• A plain AI disclosure near the start of the call.
• The model is not the final decision-maker on anything that could be an adverse action.
• Retention terms for audio and transcripts, and awareness of all-party-consent states.

6. Telephony and data handling

• Does it bridge to your existing phone number, or force a new one? What's the CPaaS dependency?
• Where do audio and transcripts go, which sub-processors touch them, and is audio used to train the vendor's models (can you opt out)?

7. Languages and accents

• Which languages does it genuinely handle well, and does the vendor report containment and error rates per language and accent group rather than a single blended number?
• An 80% aggregate can hide 45% for one caller segment.

8. Observability

• Can you see individual call transcripts, the reason for each escalation, and containment trends over time, or only a summary dashboard?
• Can you export the transcripts and the call data if you leave?

9. Evaluation and pricing

• Can you run it against your own historical call transcripts and see containment and error rates?
• Per-minute pricing, and how the bill behaves at your peak call volume.

How to weight it

Mostly-informational call volume makes sections 1, 2, and 5 the decision. Calls that qualify applicants or touch a decision make sections 3, 4, and 5 the whole thing: a vendor that can't act under your rules or hand off cleanly isn't a fit regardless of how smooth the demo was. Our voice AI engagement was scoped around exactly that: native speech-to-speech, actions through the client's own APIs, and a warm handoff triggered before any adverse-action line.

Red flags

• The demo is over wifi, not a phone line.
• "It handles compliance" with no specifics on consent records or the decision boundary.
• They won't run your historical transcripts.
• Cold transfer on escalation.
• Pricing that won't be quoted at your peak volume.

Where this checklist misleads

• Feature-counting. Weight by your actual call mix, not the longest capability list.
• A curated demo. Insist on your own transcripts and a live pilot on one intent.
• The smallest call volumes. A menu-based IVR may still be the right call.

FAQ

Build or buy, which does this point to? Either. Score vendors with it, or use the same questions as build requirements.

What's the single most important item? Native low-latency speech and a real warm handoff. Those two decide whether callers tolerate the line at all.

How long should evaluation take? Long enough to run your own historical transcripts and a live pilot on one intent group: weeks, not a demo call.

ISTRALLEN builds voice agents to this bar for financial-services call centres; see AI for Fintech.