Are these real phone calls or browser calls?

Real phone calls — PSTN/SIP. The recipient hears a normal phone ring on their phone; the AI is on the line.

Can the AI handle interruptions and overlapping speech?

Yes — barge-in is supported and tuned. The AI yields when interrupted and handles overlapping speech naturally.

Can it leave a voicemail if no one picks up?

Yes — voicemail detection and a configurable voicemail message are supported on outbound calls.

How is latency under 200ms possible?

Direct SIP/RTP path, multi-region endpoints, streaming TTS, and an LLM fast-path that produces partial output the AI can start speaking before the full thought is done.

Can I record AI phone calls for compliance?

Yes. Recording is configurable per number / agent / call, with PII redaction available on the transcript.

Will it work in countries my carrier reaches?

Yes. The PSTN leg stays on your carrier (or one we provide), so coverage matches your carrier's footprint. We have customers running in 100+ countries.

Use case

AI Phone Calls

Real AI phone calls — inbound and outbound — with your existing carrier and tools. Sub-200ms latency, 100+ languages, deployable in minutes.

Try now

Median latency: <200ms
Concurrent calls: 500+
Languages: 100+
Carriers supported: 37+

01 — Overview

How do AI phone calls actually work?

An AI phone call is a real PSTN/SIP call where one side is an AI agent. The carrier handles the audio, the AI handles the conversation. Open runs both inbound (the AI picks up) and outbound (the AI dials), end-to-end.

On an inbound AI phone call, your existing carrier (Twilio, Vonage, RingCentral, Zoom Phone, your trunk) routes the SIP INVITE to Open's endpoint. The AI picks up in under two seconds, greets the caller in your brand voice, listens, and runs the conversation. Mid-call it can look the caller up in your CRM, check an order, book a calendar slot, send a payment link, or warm-transfer to a human. The audio path stays direct between the carrier and Open — no extra proxy, no added latency.

On an outbound AI phone call, Open dials the recipient through your carrier (or a carrier we provide), presents an approved caller ID, and starts the conversation when the recipient picks up. Use cases include lead callbacks, appointment confirmations, payment reminders, post-purchase surveys, win-back campaigns, KYC verification calls. You can place calls one at a time via the dashboard or in bulk via the API.

Latency is what determines whether the call feels human. Median first-token reply latency is under 200ms on US and EU regions; tail latency stays under 500ms. The recipe is direct SIP/RTP (no proxy hops), streaming TTS, and an LLM fast-path that doesn't wait for a full thought before starting to speak.

Languages are not an upcharge. Over 100 languages are supported out of the box, with mid-call switching when the caller does. Voice quality is tuned per language so the AI doesn't sound like an English-speaker reading phonetic Spanish.

Compliance is built-in. PII redaction on transcripts before they leave Open. SOC 2 Type II, GDPR-aligned, HIPAA- and PCI-ready with the right configuration. Recording can be disabled per number, per agent, or per call.

What stays the same

Your carrier and numbers
Bring any of 37+ supported carriers. Numbers don't port. The PSTN leg stays where it is.
Your CRM, calendar, helpdesk
Open uses your existing tools via official APIs. The CRM stays the system of record.
Your reporting
Carrier-side call logs continue. Open adds AI-side reasoning traces and outcome tags on top.
Your team
Your agents handle escalations only. Routine calls don't reach them anymore.

What changes with AI calls

AI is on the line
Greets, listens, runs your tools, and replies in natural speech in 100+ languages.
Sub-200ms reply latency
Direct SIP/RTP, streaming TTS, fast-path LLM — the call feels like a human conversation.
Warm transfers
When humans take over, they get the live transcript and detected intent on SIP REFER.
Per-call observability
Every call recorded, transcribed, and trace-logged. You can replay why the AI made a decision.

02 — Why it works

What makes Open the right use case answer

Inbound and outbound, one product
Pick up calls from your carrier, dial out through it. No separate dialer, no separate IVR replacement.
Latency tuned for real conversations
Median <200ms reply. The AI starts speaking as soon as it has enough thought to say something useful.
Carrier-agnostic
37+ carriers as first-class SIP destinations. Bring what you already run.
Compliant and observable
Recording, redaction, reasoning trace, SOC 2 Type II, GDPR/HIPAA/PCI-ready. Backed by the Open $2M refund guarantee.

03 — Security

Encrypted, audited, refundable

SIP over TLS for signaling, SRTP for media. Every call logged with full reasoning traces. SOC 2 Type II, GDPR-aligned, HIPAA- and PCI-ready. Backed by the Open $2M Refund Guarantee.

04 — FAQ

AI Phone Calls questions, answered

More voice AI guides

Use caseAI Voice AgentA production-grade AI voice agent that runs real phone calls — inbound, outbound, and warm transfers — using your tools live, in your brand voice.Use caseAI ReceptionistAn AI receptionist that picks up on the first ring, books appointments, qualifies callers, and hands off to a human only when one is needed.Use caseAI Outbound CallingAI outbound calling for the calls humans currently dial — callbacks, payment reminders, post-purchase, KYC, win-back, surveys. Fully observable, fully integrated.Use caseAI Call CenterAn AI call center that answers calls in under two seconds, runs your tools live, and escalates with full context. No per-seat fees, no migration.PlatformVoice AI PlatformA voice AI platform with the SIP, the tooling, the analytics, and the compliance already wired. Configure the agent — not the plumbing.Use caseAI Answering ServiceA 24/7 AI answering service that picks up every call, captures the message, books the appointment, and pages a human only when one is genuinely needed.