Add an AI voice agent to your existing FreePBX or Asterisk
You do not need to replace your phone system to add an AI voice agent. If you run FreePBX, Asterisk, or any SIP-capable PBX, you connect it to Vio over a SIP trunk: your PBX keeps handling your extensions and carrier exactly as it does today, and it hands the specific numbers or extensions you choose to a Vio AI agent that answers, qualifies, and routes the call. There is no number porting and no change to your existing carrier.
This is a bring-your-own-carrier (BYOC) setup. Your telephony minutes stay on your PBX and carrier at your existing rates — Vio meters only the AI. See Pricing.
Why bridge instead of replace
Most businesses running FreePBX or Asterisk have years of configuration, IVR trees, extensions, and a carrier contract they don’t want to touch. You don’t have to. Bridging over a SIP trunk means:
- Your PBX stays the system of record. Extensions, ring groups, and your carrier are unchanged.
- You choose exactly what the AI answers — one DID, an overflow queue, an after-hours route, or a single extension. Everything else keeps ringing your humans.
- No porting. You keep your numbers and your negotiated per-minute rates.
- It’s reversible. Point the route back at your queue and the AI is out of the path.
What you need
| Requirement | Detail |
|---|---|
| A SIP-capable PBX | FreePBX, Asterisk, 3CX, or any PBX that can create a SIP/PJSIP trunk. |
| A Vio account | To create the trunk and build the agent that answers. |
| Network reachability | Your PBX must be able to reach Vio’s SIP host over the internet, and your firewall must allow the SIP and RTP media ports. |
| A number or extension to hand over | The DID or internal extension whose calls the AI should answer. |
Connect FreePBX (or Asterisk) to Vio
Create the trunk in Vio
In Vio, open SIP Trunks → New trunk. Vio issues you an inbound host, username, and password. Inbound trunks require digest authentication — this is what stops anyone else on the internet from sending calls into your agent. Keep these credentials private. See SIP trunks (BYOC) for the full reference.
Add a matching SIP trunk on your PBX
In FreePBX, go to Connectivity → Trunks → Add SIP (chan_pjsip) Trunk. Create a trunk pointing at the Vio host from the previous step, and set the username and password to exactly the credentials Vio issued. On plain Asterisk, add the equivalent trunk in your pjsip.conf (an endpoint, auth, and aor pointing at the Vio host with the same credentials).
Route the calls you want the AI to answer
Decide which calls the AI should take, and route only those to the Vio trunk — the rest of your dialplan is untouched. Common choices:
- A whole DID — send an inbound route for that number to the Vio trunk.
- Overflow — route your queue’s overflow or after-hours destination to the trunk so the AI catches calls your team can’t.
- One extension — forward a single extension to the trunk.
Build the agent and assign it
In Vio, create the agent that should answer — its greeting, persona, the data it collects, and any tools it can use mid-call. Assign it to the number or trunk in Phone numbers.
Place a real call and confirm
Call the number you routed. You should hear the agent greet the caller within a ring or two, with two-way audio. The call then appears in your call log with its transcript, recording, summary, and cost.
Outbound calls from your PBX
The steps above put the AI on inbound calls. If you also want Vio to place calls through your FreePBX or Asterisk — for a campaign or a callback — give Vio your carrier’s outbound host on the same trunk, and make sure your PBX permits outbound routing for the calls Vio will send. Your PBX needs a peer that accepts calls from Vio and an outbound route with a real PSTN path for the numbers you’ll dial; without that route your PBX will reject the call. Inbound answering works on its own and does not depend on this.
Keep your inbound trunk username and password private — they authenticate calls into your agent. If you think they’ve leaked, rotate the inbound password in Vio and update your PBX trunk to match.
Call quality on a phone line
A normal phone call is narrowband by nature — the public phone network compresses voice, so no phone call sounds studio-HD on the line itself. This is true of every phone system, not a Vio limitation. The agent still comes through clearly, and the recordings in your call log are captured at higher fidelity than the live line. See Troubleshooting if a specific call sounds wrong.
Frequently asked
Q. Do I have to replace FreePBX or Asterisk to use an AI voice agent? No. Vio connects to your existing PBX over a SIP trunk, so your extensions, dialplan, and carrier stay exactly as they are. You route only the calls you want the AI to answer to Vio, and everything else keeps working as before. There is no rip-and-replace.
Q. Do I need to port my phone numbers? No. Your numbers stay on your PBX and carrier. You point the specific DIDs or extensions you want the AI to handle at the Vio trunk, and keep your existing numbers and per-minute rates. Nothing is ported and the change is reversible.
Q. Can the AI answer just one number and leave the rest to my team? Yes. You decide exactly what the AI takes — a single DID, an overflow or after-hours route, or one extension. Every other call keeps ringing your humans, because the routing lives in your own PBX dialplan, not in Vio.
Q. Can Vio also make outbound calls through my PBX? Yes, if your PBX permits it. Give Vio your carrier’s outbound host on the trunk, and make sure your PBX has an outbound route with a real PSTN path for the numbers Vio will dial. Inbound answering works without any of this; outbound just needs that route in place on your side.
Q. Is connecting my PBX to Vio secure? Inbound trunks require digest authentication, so only your PBX — with the credentials Vio issued — can send calls into your agent. Keep the username and password private, and rotate the inbound password if you suspect they have leaked.
Q. What does it cost to run the AI on my existing lines? You pay Vio for the AI per minute — ₹4.25/min on the standard engine — and your telephony minutes stay on your own carrier’s bill at your existing rates, because the call rides your trunk. See Pricing.
Next step
Ready to connect a trunk? Follow the full SIP trunks (BYOC) reference, then build your agent and test it on a real call.