Does this work with 3CX self-hosted?

Yes. Open registers as a standard SIP trunk regardless of how 3CX is hosted.

Does this work with 3CX-hosted plans?

Yes. The integration is identical.

Can I keep my existing PSTN provider?

Yes. Whatever carrier you use for inbound/outbound (Twilio, Telnyx, RingCentral, a local carrier) keeps providing PSTN. Open is just an additional internal SIP trunk.

Do I need extra 3CX licenses for the AI?

No, beyond perhaps a virtual extension for routing — which most 3CX licenses already include in their concurrent calls budget.

Can the AI escalate to my 3CX extensions?

Yes. SIP REFER returns the call to a 3CX queue, ring group, or extension with the transcript attached.

What does this cost on top of 3CX?

3CX licensing is unchanged. Open charges per resolved conversation.

Is the SIP signaling secure?

TLS and SRTP are both supported.

How long does setup actually take?

Inbound is typically 15–20 minutes once the SIP trunk is registered.

Legacy / Enterprise

Open for 3CX

Add Open as a SIP trunk and outbound rule in your 3CX PBX and the AI picks up — extensions, ring groups, and digital receptionists stay yours.

Try now

Setup time: Under 20 minutes
Auth: Digest credentials or IP allowlist
Directions: Inbound · Outbound · Call transfer
Pricing: Included with Open

01 — Overview

Can I add an AI phone agent to my 3CX PBX?

Yes. 3CX speaks plain SIP, so Open registers as a standard SIP trunk. Your extensions, digital receptionist, ring groups, and dial plan stay exactly as they are.

3CX remains your PBX. Extensions, queues, ring groups, the digital receptionist (IVR), and the 3CX management console all stay where they are. Open joins as a SIP trunk — practically that means a new SIP Trunk entry in 3CX → SIP Trunks, plus an outbound route or a digital-receptionist branch that targets it. Opted-in calls flow through Open; everything else keeps working untouched.

For inbound, the cleanest pattern is to set up a digital-receptionist option (or a DID inbound rule) that forwards to a virtual extension routing to the Open SIP trunk. Inbound calls hit 3CX, take the AI branch, and Open answers. The 3CX call recording and call reporting still see the leg.

For outbound, Open opens a SIP session against the same 3CX SIP server using a registered SIP trunk credential. Outbound rules in 3CX dictate which calls Open can place, with whatever caller IDs you've configured.

What the AI does on the call: it listens, reasons over your knowledge base and connected tools (CRM, ticketing, calendar, payments), and acts. When the AI needs a human, it warm-transfers back to a 3CX queue or extension via SIP REFER with the live transcript and detected intent attached.

Billing stays predictable. 3CX licensing / hosting fees are unchanged. Open charges per resolved conversation. If you're using a third-party SIP provider for PSTN (e.g. Twilio Elastic SIP Trunking), those minutes still bill on that provider; Open never marks them up.

What stays the same on 3CX

3CX extensions and queues
Existing extensions, queues, ring groups, and digital receptionists stay in place.
3CX management console
You manage the PBX the same way.
Existing PSTN trunks
Whatever SIP provider you use today (Twilio, Telnyx, RingCentral, a local carrier) keeps providing PSTN.
Reporting and recording
3CX call recording and analytics keep working.

What's new with Open

A new SIP Trunk in 3CX
Open is registered as a SIP trunk in 3CX → SIP Trunks.
Inbound rule / DR branch
On the digital receptionist branch or inbound rule you opt-in, Open is the destination.
AI handles the conversation
The AI greets, listens, calls your tools, and replies in natural speech.
Pricing model
Open per resolved conversation. 3CX licensing and your existing PSTN minutes stay where they are.

02 — Why this works

The native 3CX experience

Native SIP — 3CX speaks it fluently
Open registers as a generic SIP trunk; no custom modules required.
Per-DR branch opt-in
Pick exactly which digital receptionist branches or inbound rules get AI.
Self-hosted or 3CX-hosted
Works the same whether you run 3CX in your own VM or on the 3CX-hosted plan.
Warm transfer back to 3CX queues
AI escalations come back into a 3CX queue or extension via SIP REFER with the transcript attached.

03 — Setup guide

Wire up 3CX in under 20 minutes

Two trunks — one inbound, one outbound. Both configurable from Settings → SIP in the Open dashboard.

1
Open Settings → SIP
Open the inbound trunk configuration.
2
Pick a SIP region
Choose Global, US, EU, or APAC.
3
Copy the SIP credentials
Grab the SIP endpoint, username, and password.
4
Add a SIP Trunk in 3CX
In 3CX Management Console: SIP Trunks → Add SIP Trunk → Generic SIP Trunk → enter Open's SIP host and credentials.
5
Pick the digital receptionist branch
Decide which DR branch or inbound rule should route to AI.
6
Route the branch to the trunk
Set the branch's destination to the new SIP trunk (or to a virtual extension that forwards to it).
7
Add the matching numbers to Open
Under Phone Number (DID), add the 3CX DIDs that fronted the DR branch.
8
Assign numbers to an AI agent
Channels → Phone → Agents → assign DIDs.
9
Place a test call
Dial a 3CX number, take the AI branch, and confirm Open answers.

04 — Configuration

Settings → SIP, at a glance

A real inbound trunk for 3CX looks something like this. Yours are generated when you open Settings → SIP.

Inbound trunk · 3CX

Sample

SIP endpoint: sip.us.opencx.comUS region
Transport: TLSrecommended
3CX trunk type: Generic SIP Trunk
Username: open_inbound_3cx…
Password: ••••••••••••••••

05 — Security

Encrypted, audited, refundable

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

06 — FAQ