Voice Agent Settings

This page covers the settings in the General, Model Settings, and Advanced Settings tabs. The guiding principle: the defaults are tuned for natural conversation — change a setting only when you observe the specific problem it solves. Each section below tells you what that problem looks like. The Evaluation tab is a separate, policy-driven grading system for completed calls — it’s covered on its own page: Voice Agent Evaluation.

General

Setting	What it does	Guidance
Name / Description	Internal identification — callers never see these.	Name by use case and audience (“Loan reminder — VN retail”), not just “Test 2”.
Region	Where the call infrastructure runs: US or South East Asia.	Pick the region closest to your callers, not your office — it directly affects audio latency.
System Prompt	The instructions driving the whole call (Single Prompt engine). Supports `{{contact}}` placeholders.	The single highest-leverage setting. Specifics beat length; include what the agent must never do.

Model Settings

Speech Recognition

Configures how the agent understands spoken input.

Setting	Default	When to change
Provider / Model	Revve’s default STT	Rarely. Change only if a specific language or accent performs poorly and Revve support suggests an alternative.
Language	—	Always set this to your callers’ language. Wrong language = garbage transcription = nonsense answers.
Key Terms	Empty	Add comma-separated brand names, product names, and jargon the transcriber keeps mishearing (check Preview transcripts to find them).

AI Model

Setting	Default	When to change
Provider / Model	—	Faster models keep the conversation snappy; more capable models handle complex policies better. If callers experience long pauses before answers, try a faster model before touching timing settings.
Temperature	0.7 (range 0–2)	Lower toward 0.3 for compliance-sensitive calls where wording must stay consistent (collections, banking). Raise above 0.7 only for deliberately casual small-talk agents — high values risk the agent drifting off script.
Max Tokens	4096	Leave it. Long maximums don’t make the agent talk longer — your prompt controls that.

Voice Synthesis

Setting	Default	When to change
Provider / Model / Language / Voice	—	The voice is your brand on the phone. Test 2–3 candidates with your actual script in Preview — voices that sound great reading a sentence can stumble on your product names.
Speed	Provider default	Slow down slightly for older audiences or complex information (amounts, dates); speed up slightly for short reminder calls.
Pronunciation Dictionary	Empty	Add entries when the voice mispronounces something — your company name, a product, a person. Map the written form to a phonetic spelling. Fix mispronunciations here, not by re-spelling words in your prompt.

Advanced Settings

Advanced Settings is organized into sections in a left sidebar. The impactful ones in detail:

Call Behavior

Setting	Default	When to change
Max Duration	5 minutes (1–60)	Raise for support or interview agents that legitimately need long calls. Keep short for outbound campaigns — it caps cost when a call goes nowhere.
Begin Delay	1000 ms	Leave it — it gives the connection a beat to stabilize before the agent speaks.
End After Silence	10 s (5–300)	How long dead air is tolerated before hanging up. Raise if your flow includes steps where callers go quiet legitimately (finding their account number).

Conversation

This section controls the feel of the conversation — it’s where voice agents are won or lost. Conversation Start

Setting	Default	Guidance
AI Speaks First + Initial Greeting	Off	Turn on for outbound calls (the agent called, it should explain why). For inbound, answering with a greeting is also the norm — most agents want this on with a short, branded greeting.
Allow caller to interrupt the greeting	Off	Sub-toggle under AI Speaks First. Off: the greeting always plays in full. On: callers can barge in and skip ahead. Turn on for repeat-contact outbound — callers who already know why you’re calling shouldn’t have to sit through the pitch. Keep off when the greeting carries required disclosures.

Turn Handling — how the agent decides the caller finished speaking, and how fast it replies:

Setting	Default	When to change
Turn detection model	Voice Activity Detection (VAD)	VAD detects silence — fast, but can cut in during natural pauses. Switch to a Smart Turn Detection model when callers are being interrupted mid-thought; it understands sentence completeness, not just silence. Three variants: English, Multilingual, and Vietnamese — the Vietnamese model is tuned for Vietnamese speech patterns and is the best pick for Vietnamese conversations.
Smart turn threshold	0.7 (0–1)	Shown when a Smart Turn model is selected; stored per speech language. How confident the model must be that the caller finished their turn before the agent replies. Agent still cutting in → raise it (waits for clearer end-of-turn cues, at the cost of slower responses). Agent feels slow to answer → lower it, accepting it may occasionally cut in. Move in 0.05 steps.
Min silence duration	0.3 s	The classic trade-off knob. Callers getting cut off mid-pause → raise toward 0.8–1.0 s. Agent feels sluggish → lower slightly. Move in 0.1 s steps and re-test. (Agents created before this field existed show 0.55 s until you save new settings.)
Min speech duration	0.05 s	Leave it — filters out clicks and pops from counting as speech.
Activation threshold	0.5 (0–1)	Raise on noisy lines (background TV, street noise triggers the agent to stop talking); lower for quiet, soft-spoken callers it fails to hear.
Prefix padding	0.5 s	Leave it — audio buffered before detected speech so first syllables aren’t clipped.
Response timing	Fixed, 0.5–3.0 s wait	”Min delay” is the shortest pause before responding; “Max delay” the longest. Tighten the max for snappy reminder calls; widen for thoughtful, consultative conversations.

Interruption Handling

Setting	Default	When to change
Interruption mode	VAD	VAD treats any voice longer than the minimum duration as an interruption. Switch to Adaptive when backchannels — callers saying “uh-huh”, “right” — keep stopping the agent mid-sentence. Adaptive ignores them.
Min duration	—	Raise it if coughs and short noises interrupt the agent.
Backchannel words	Empty	VAD mode only. Words the agent ignores as interruptions — filler acknowledgments like the Vietnamese “vâng”, “dạ”, “ạ”. Type a word and press Enter to add it. Use this when specific short acknowledgments keep stopping the agent but you want to stay in VAD mode; switching to Adaptive is the broader alternative. Empty list = suppression disabled.

Quiet Speech Handling Prompts callers who are speaking too quietly to speak up — worth enabling for audiences skewing older or soft-spoken, or calls prone to a noisy line (driving, retail floor, poor mic).

Quiet Speech Handling settings showing the Ask Caller to Speak Up toggle on, the Loudness threshold slider, and the Verbatim instruction template

Setting	Default	When to change
Ask Caller to Speak Up	Off	Detects when the caller’s voice is too quiet and prompts them to speak louder. Turn on for elderly or soft-spoken audiences, or calls likely to bury the caller’s voice in background noise.
Loudness threshold	0.50 (slider, 0–0.70)	Shown only when the toggle above is on. Minimum loudness for speech to count as “normal” — anything quieter triggers the reminder. Raise it if genuinely quiet callers aren’t triggering the nudge; the slider caps at 0.70 so you can’t accidentally flag normal conversational speech, which would otherwise loop the agent on the speak-up nudge forever.
Low-speech prompt	Verbatim mode, Vietnamese template	Shown only when the toggle above is on. Verbatim speaks fixed text word-for-word; Prompt hands the LLM an instruction and lets it generate the reply instead. Both default texts are in Vietnamese — for a non-Vietnamese agent, replace both the Verbatim template and the Prompt instruction with your own language; there’s no automatic localization.

The runtime caps this at 2 speak-up prompts per call session, so a caller who stays quiet won’t get nagged repeatedly. Silence Handling

Setting	Default	When to change
Follow Up on Silence	Off	Turn on for outbound and qualification calls — the agent re-engages (“Are you still there?”) instead of waiting out the clock.
Silence Timeout / Max Follow-ups	5 s / 3	Defaults are right for most flows.

Environment

Setting	Default	When to change
Noise Cancellation	Off	Turn on when callers are in noisy environments (drivers, retail floors) and transcription quality suffers.
Ambient Sound	None	Adds background ambience (office, city) to the agent’s side. A subtle office ambience can make an agent feel less sterile; skip it unless you’ve A/B-listened.

Voicemail

Off by default — when voicemail is detected the call simply hangs up. Enable voicemail detection to leave a message instead:

Voicemail Message supports {{contact}} placeholders — for example: “Hi {{firstName}}, this is Acme calling about your application…”
Detection Timeout (default 5000 ms): how long to listen before deciding it’s a machine. Leave it unless detection misfires.

For outbound campaigns, enabling voicemail is usually worth it — a personalized message measurably improves callback rates versus silent hangups.

Call Transfer

Lets the AI hand the call to a human, with a spoken handover message:

Setting	Options	How to choose
Transfer To	Revve User (in-app agent) / SIP Address / Phone Number	Revve User routes the call to an available human agent in the Revve app — no external number needed. SIP Address targets a SIP endpoint. Phone Number dials an external number in E.164 format (`+84775352590`).
Transfer Type	Bridge Transfer (default) / Cold Transfer	Bridge: a warm consult transfer — the caller is held with music while the AI privately briefs the human with the call summary, then connects them and goes silent (but keeps logging). Cold: the call is handed off entirely, no further logging — choose this for compliance contexts where the AI must fully exit.
Transfer Message	Free text	What the AI says before transferring (“Let me connect you with a specialist — one moment.”). Always set one; silent transfers feel like being hung up on.

See Call Transfer for the full warm-transfer workflow, including how in-app agents receive and accept transfers.

Everything else

The remaining sections are covered in depth on Voice Agent Advanced Capabilities — the short version:

Section	What it’s for
Phone Number	Pick the outbound caller ID — a single team number or a number pool (a random pool number per call).
Phone Verification	Confirm the caller’s identity by having them state their phone number, checked against the number already on file for that contact.
Normalization	Normalize spoken data like addresses and license plates into structured formats.
Retry & Callback	Auto-retry failed outbound calls (busy, no answer, failed) and let customers request callbacks.
Tools	Attach custom tools (API calls, SMS sending) the agent can use mid-call, plus presets: two calendar tools, a ticket-creation tool, and a deterministic value-validation tool. Not every preset in the dropdown works on a phone call — see Voice Agent Tools before you attach one.
Webhook	Send call events to a URL on your side.
Analysis & Summary	Configure the post-call summary and the data fields extracted from each call (these appear in Call History).
Security	Sensitive-data handling for this agent’s calls.
Notification	Alert your team about call outcomes.

A tuning workflow that works

Ship with defaults. Make 5–10 test calls in Preview, including a noisy-environment call from your phone.
Read the transcripts. Transcription errors → fix Language/Key Terms first; everything downstream depends on hearing correctly.
Fix the single most annoying rhythm problem (cutting off / sluggishness) with one turn-handling change, re-test, repeat.
Only then polish: voicemail message, transfer message, pronunciation dictionary.

What’s Next

Voice Agent Evaluation — automatically grade completed calls against a weighted set of metrics.
Voice Agent Tools — every Tools-tab preset, and which ones don’t work on a phone call.
Call Transfer — the full warm-transfer workflow, including routing to in-app agents.
Do Not Call List — the team-wide list every outbound call is checked against before it’s placed.
Creating a Campaign — drive outbound calls with your tuned agent.

Getting Started

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Voice Agent Settings

General

Model Settings

Speech Recognition

AI Model

Voice Synthesis

Advanced Settings

Call Behavior

Conversation

Voicemail

Call Transfer

Everything else

A tuning workflow that works

What’s Next

​General

​Model Settings

​Speech Recognition

​AI Model

​Voice Synthesis

​Advanced Settings

​Call Behavior

​Conversation

​Voicemail

​Call Transfer

​Everything else

​A tuning workflow that works

​What’s Next

General

Model Settings

Speech Recognition

AI Model

Voice Synthesis

Advanced Settings

Call Behavior

Conversation

Voicemail

Call Transfer

Everything else

A tuning workflow that works

What’s Next