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AI VOICE AGENT DEVELOPMENT

AI Voice Agents

Calls go unanswered after hours and hiring more phone staff does not scale. A voice agent only helps if it survives latency, interruptions and the moment it has to hand off - the three things demos skip.

3 things we build first: latency budget, barge-in, handoff rule
TODO production voice-agent benchmark - published once a reference build ships
TODO average task-completion rate - measured per deployment

Scope a PoC

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IN SHORT
  • What we build: production voice agents with a latency budget, barge-in handling and a defined handoff.
  • Who for: ops and CX leads at any business with high inbound call volume.
  • In what timeframe: a scoped PoC scored against a real-call scenario suite before it goes live.
01 / THE TRAP

Why most ai voice agents projects fail in production

No latency budget

Each hop - transcription, inference, speech synthesis - adds delay, and an unbudgeted pipeline crosses the point where the caller hears a pause and disengages.

No barge-in handling

Real callers interrupt. An agent that finishes its scripted line while the caller is talking reads as a machine and gets escalated immediately.

No handoff rule

Every voice agent hits a request it cannot complete. Without a defined threshold and a warm handoff, it either stalls or confidently does the wrong thing.

02 / METHOD

How we build ai voice agents

Latency-first pipeline

We budget round-trip time at design and choose transcription, model and TTS to fit it, with a fallback path when a hop is slow.

Turn-taking & barge-in

The agent yields the moment the caller speaks, re-listens, and tracks intent across interruptions rather than replaying a script.

Grounded responses

Answers are grounded in your own content and account data, so the agent is accurate on your specifics, not just fluent in general.

Handoff & escalation

A confidence threshold and authorisation rules decide when a human takes over, with full call context passed along.

03 / EVALUATION

How we measure it

A demo passes once. Production passes ten thousand times. Every build ships with an eval harness scoring against a baseline before it goes near a user.

MetricHow we measure it
Task-completion rateShare of calls the agent resolves end-to-end on a scenario suite drawn from your real call types.
Round-trip latencySpeech-in to speech-out, measured per hop against a fixed budget, not just averaged.
Handoff accuracyFalse-handoff and missed-handoff rates - escalating what it should, and only what it should.
Transcription accuracyWord error rate on your vocabulary: product names, account formats, local place names.
04 / AUTONOMY BOUNDARY

Where the agent stops

Handled end-to-end

  • Answering routine inbound questions after hours
  • Booking, rescheduling and confirming appointments
  • Capturing and qualifying lead details
  • Routing to the right team with context

Always goes to a human

  • Anything below the confidence threshold
  • Requests it is not authorised to complete
  • Any explicit request for a person
  • Payment or account changes
05 / STACK

Stack

Speech
Streaming STTLow-latency TTSBarge-in / VAD
Reasoning
ClaudeGPTOpen-weight fallback
Telephony
SIP / PSTNTwilioWebRTC
Ops
Eval harnessCall loggingLatency monitoring

Model-agnostic by default, with a fallback path and cost controls wired in — we pick per use case on latency, cost and data-handling, not a default vendor.

06 / FIT

Industries where this pays off

AI for Car DealershipssoonAI for FintechAI Customer Support Automationsoon
07 / PROOF

Benchmark in progress

PROOF IN PROGRESS

A published latency-and-completion benchmark for a reference voice build is in progress - and until it exists we will not quote a number we cannot reproduce. What we can show today is the architecture: a budgeted latency pipeline, barge-in handling and a hard handoff rule, evaluated against a real-call scenario suite before anything goes live. Scope a PoC and the first deliverable is that eval on your own call types.

08 / FAQ

FAQ

Why do most AI voice agents fall apart on real calls?

Three things a demo never tests: latency, interruptions and handoff. A caller will not wait two seconds for a reply, will talk over the agent, and will occasionally need something the agent cannot do. If the build has no latency budget, no barge-in handling and no hard handoff rule, it sounds fine in a scripted demo and fails on the first real call. We build those three first.

What is an acceptable response latency for a voice agent?

Round-trip latency - speech-in to speech-out - needs to stay low enough that the caller does not perceive a pause, which in practice means budgeting every hop: transcription, model inference, and text-to-speech. We set a latency budget at design time and measure against it in the eval harness, because a correct answer that arrives two seconds late still reads as a broken call.

Can the agent handle being interrupted mid-sentence?

Yes - barge-in handling is a first-class requirement, not a nice-to-have. The agent stops speaking when the caller starts, re-listens, and picks up the new intent rather than finishing its scripted line. Without it the agent talks over people, which is the single fastest way a caller loses trust and asks for a human.

When does the agent hand off to a person?

On a defined rule, not a guess. Anything below a confidence threshold, any request the agent is not authorised to complete, and any explicit ask for a human triggers a warm handoff with the full call context passed along, so the caller does not repeat themselves. The handoff rule is the product decision that makes a voice agent safe to put on your main line.

How do you measure whether the voice agent is good enough to ship?

Against a scenario suite built from real call types, scored before it goes live: task-completion rate, latency, false-handoff and missed-handoff rates, and transcription accuracy on your vocabulary. It ships when it clears the baseline on that suite, and every prompt or model change is re-scored against it - so improvements are measured, not assumed.

Which industries get the most value from a voice agent?

Any business with high inbound call volume where calls go unanswered after hours and adding phone staff does not scale - dealership service lines, field-service dispatch, and dental or clinic front desks are common. Those are the verticals where a missed call is a lost customer and a voice agent that handles the routine calls pays for itself quickly.

See it pass an eval, not a demo.

A scoped PoC with the eval harness attached — timeline and scope on the call, no price on the page.

Scope an AI PoC →