An AI Reply Assistant That Replies to Every Caller in Seconds

5.0

ON G2

AI reply assistants draft your emails, chats, and comments. They leave the reply that cannot wait, the ringing phone, unanswered. Retell AI is the AI reply assistant for your phone line: a voice agent that replies to every caller live in natural conversation, calls back every missed call and web inquiry within seconds, answers questions, books appointments, and routes the call. It replies on your existing number, 24/7, in 31+ languages, so no caller and no inquiry waits on a response. It does not draft written replies for you to send; it replies to callers by voice, on its own.

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Trusted by over 3,000 businesses powering 30+ million calls per month.

How It Works

Go from build to a live reply in a day, on your existing number.

Build the agent

Point the agent at your website, FAQ, hours, and pricing through a knowledge base that syncs as that content changes, so it replies the way your team would. Define the flow with a drag-and-drop builder: greeting, intent detection, the answers you want it to give, booking, and routing, then connect your calendar and CRM. No engineering team is required for a standard agent.

Test against your real callers

Run the agent through simulation against the calls you actually get: a pricing question, a booking, a missed-call callback, an upset caller, and a request for a person. Each run shows how it replies and what it books, so you fix the flow and validate at volume rather than finding gaps on live callers.

Connect your line and inquiry sources

Connect your line through SIP trunking and let the agent reply to inbound calls, then wire your missed calls and web forms to trigger an outbound callback within seconds. Set the conditions for human handoff, go live on one line or one inquiry source, confirm the reply quality, then expand.

Monitor and retrain

Every reply is transcribed, summarized, and tagged by outcome through post call analysis, and every booking and callback syncs to your CRM. Track reply rate, callback speed, booking rate, and transfer rate in a dashboard, then retrain the flow on the calls the agent fumbles.

Use Cases

Reply to every inbound call live

The agent picks up on the first ring and replies in natural conversation, so the line never goes to voicemail or a busy signal. It answers hours, pricing, and service questions from the connected knowledge base instead of a static phone-tree script, and handles overflow through an AI answering service so a rush of calls all gets a reply at once.

Call back every missed call and web inquiry in seconds

The agent triggers an outbound callback the moment a call is missed or a web form is submitted, while the person is still paying attention, so you reply faster than the next business. It can reach a whole list of inquiries at once through batch call campaigns for follow-ups and re-engagement.

Reply with an action, not just words

The agent checks live availability and books appointments on Cal.com or Google Calendar during the call, then sends a confirmation. It looks up and updates records mid-call, texts the caller a confirmation or follow-up where it helps, and hands the calls that need a person to the right team with a warm call transfer that carries the full context.

Reply 24/7, in any language

The agent answers nights, weekends, and holidays, so an after-hours caller gets a live reply instead of a callback tag, and replies in 31+ languages with automatic language detection so callers are answered in the language they start in.

Keep every reply consistent and on-brand

Every reply stays consistent and on-brand, in one of 100+ lifelike voices or a clone of your own, so callers hear the same voice and the same answers on every call.

Re-engage leads with outbound follow-ups

Beyond inbound, the agent runs follow-ups and re-engagement across a whole list through batch call campaigns, so a stale lead still gets a timely reply by phone.

Compliance

Calls are transcribed for your records, on a platform built to protect them.

SOC 2 Type II

Call data runs on SOC 2 Type II certified infrastructure, meeting enterprise security requirements.

GDPR

Caller data is processed under GDPR, covering consent and access rights for callers in the EU.

PII Redaction

Sensitive details are masked in transcripts automatically, alongside single sign-on and role-based access.

Feature

Why teams choose Retell AI to reply on the phone

Build

Deploy

Monitor

Replies with an action, not just words

A reply here is not a drafted message waiting for your approval. The agent books the appointment, updates the record, or routes the call during the conversation, then logs it through CRM sync.

Replies in seconds, not hours

The agent calls back a missed call or a new web lead the moment it lands. Responding while the inquiry is fresh makes a contact far more likely to convert than a reply that comes an hour later.

Replies in roughly 600 milliseconds

End-to-end latency of about 600ms with proprietary turn-taking means callers do not sit through dead air, and in testing many do not realize they are speaking with AI at all.

A fraction of a person on the phones

A live answering service runs about $1.20 to $2.50 a minute. The agent replies from $0.07 a minute and covers nights and weekends too.

Never leaves an inquiry without a reply

The agent answers every call and calls back every missed one, then tracks reply rate, callback speed, booking rate, and transfer rate in a dashboard. That matters because callers who hit voicemail rarely call back, and industry research puts the average missed call at about $12.15 in lost value.

Integrations

Seamless 
Integrations with Your
Tech Stack

View All Integrations

Hubspot
Twillio
Vonage
Go High Level
8n8
Zapier
Salesforce

Hubspot
Twillio
Vonage
Go High Level
8n8
Zapier
Salesforce

Avaya
Genesys
Five9
Amazon Connect
Telnyx
Make
Cal.com

Avaya
Genesys
Five9
Amazon Connect
Telnyx
Make
Cal.com

Pricing

Cut Costs by 90% with AI phone Agents

Pay as you go

$0 to start.

$0.07–$0.12 per minute – Pay only for what you use.

60 mins of free access.

20 concurrent calls.

10 Free Knowledge Bases.

Get Started

Enterprise Plan

For companies with large volumes, data or deployment requirements, or support needs.

White glove service for your use case.

Premium support with dedicated solution engineer teams.

Custom pricing and concurrent calls based on your needs

Talk To Sales

FAQ

Frequently asked questions.

What is an AI reply assistant?

The term covers two different tools. One is a writing assistant that drafts replies to emails, chats, and comments for you to review and send. The other is a phone assistant that replies to callers live, the moment they call. Retell is the second kind: a voice agent that answers your calls, calls back missed ones, and replies in natural conversation, booking and routing during the call. It differs from a chatbot or a draft generator because it speaks, listens, and acts in live conversation.

Does it draft my email or text replies?

No. It replies to phone calls in live voice, and it can send an SMS confirmation or follow-up after a call. It does not draft written replies to your emails, chats, or social comments. For that, use a writing tool, and let Retell own the phone channel those tools leave unanswered.

Does it reply automatically, or do I approve each reply?

It replies live, on its own, within the rules you set. There is no draft to approve mid-call. You decide what it can say and when it should transfer to a person, and it follows those rules on every call.

How fast does it call back a missed call or web lead?

Within seconds, through a webhook trigger from your phone system or web form. A reply that lands while the person is still paying attention converts far better than one that comes an hour later.

Is an AI reply assistant the same as an answering service?

It does the job of one and more. A traditional answering service takes a message; this agent replies, answers the question, books the appointment, and routes the call in live conversation.

How much does it cost?

Pay-as-you-go at $0.07 per minute with no platform fee or contract, plus $10 in free credit to start. You pay for minutes worked, not seats.