***

title: SIP Integration
slug: about-sip
description: >-
Learn how to connect your own telephony provider to Synthflow AI using SIP
trunking.
---------

<Check>
  **Enterprise Feature:** SIP/PBX integration requires an Enterprise plan subscription. [Contact our sales team](https://synthflow.ai/talk-to-sales) to enable this feature.
</Check>

Synthflow AI supports **SIP (Session Initiation Protocol)** integration for enterprise customers. This allows you to:

* Bring your own VoIP provider (e.g. Twilio, Telnyx)
* Use existing business phone numbers
* Integrate with internal PBX systems (e.g. 3CX, Asterisk)
* Maintain control over your call routing and infrastructure

This setup gives you full flexibility over your telephony stack while adding Synthflow's conversational AI capabilities.

## Integration Tiers

Synthflow classifies SIP provider integrations into tiers based on validation depth and ongoing support. Check which tier your provider falls into before starting setup.

### Tier 1 — Native Integrations

Providers with a **native, validated integration** that Synthflow engineering actively tests and supports.

<CardGroup cols={2}>
  <Card title="Twilio" href="/sip-with-twilio">
    Actively tested and supported
  </Card>

  <Card title="Telnyx" href="/sip-with-telnyx">
    Actively tested and supported
  </Card>

  <Card title="RingCentral" href="/sip-with-ringcentral">
    Actively tested and supported
  </Card>

  <Card title="Vonage" href="/sip-with-vonage">
    Actively tested and supported
  </Card>
</CardGroup>

**What this means for you:**

* Integration is built and maintained by Synthflow engineering
* SIP header preservation, caller ID passthrough, and transfer flows are validated
* Documented with self-serve onboarding — standard setup timelines apply

### Tier 2 — Community-Validated Integrations

Providers that have been **successfully deployed or documented** based on real customer engagements. Synthflow has implementation experience and guides, but does not actively regression-test these integrations.

<CardGroup cols={2}>
  <Card title="Dialpad" href="/sip-with-dialpad">
    Proven in production
  </Card>

  <Card title="3CX" href="/sip-with-3cx">
    Proven in production
  </Card>

  <Card title="Aircall" href="/sip-with-aircall">
    Proven in production
  </Card>

  <Card title="Genesys Cloud" href="/sip-with-genesys-cloud">
    Proven in production
  </Card>

  <Card title="8x8" href="/sip-with-8x8">
    Proven in production
  </Card>

  <Card title="Asterisk-Based PBXs" href="/transfer-calls-between-synthflow-and-pbx">
    Proven in production
  </Card>

  <Card title="Five9" href="/sip-with-five9">
    Integration guide available
  </Card>

  <Card title="Talkdesk" href="/sip-with-talkdesk">
    Integration guide available
  </Card>
</CardGroup>

**What this means for you:**

* Setup may require Professional Services involvement
* Timelines may vary — edge cases may surface that require engineering escalation
* Not actively regression-tested by Synthflow

Synthflow supports standard SIP trunking, so any other provider offering SIP connectivity may also work. Contact our team to discuss your setup.

## Getting Started

To connect your phone numbers to Synthflow AI using SIP Trunking:

1. **Create a SIP trunk** with your VoIP provider.
2. **Configure your phone numbers** to route inbound calls through the trunk.
3. **Point the SIP trunk to Synthflow's SIP server.**
4. [**Import your numbers**](/custom-phonenumbers) into Synthflow and assign them to your agents.

This setup allows Synthflow to answer inbound calls and optionally transfer calls back to your PBX or a live agent.

## PBX Integration (Optional)

If you already use an on-prem or cloud-based PBX (e.g. 3CX, FreePBX, Asterisk):

* You can configure a SIP trunk in your PBX to route specific calls to Synthflow AI.
* This lets you use AI agents alongside your internal call flows and extensions.