SIP trunks (BYOC)
BYOC means “bring your own carrier.” A SIP trunk connects your existing carrier or PBX to Vio so calls flow through Vio’s agents while you keep your own phone numbers and your negotiated per-minute rates. If you don’t have a carrier to bring and just want to get live fast, import a Twilio number instead.
How a SIP trunk works in Vio
You connect one trunk per carrier. A trunk carries calls in two directions, and each direction is set up separately:
| Direction | What Vio gives / needs | What it does |
|---|---|---|
| Inbound | Vio issues you credentials: a host, a username, and a password. | You point your carrier at Vio using them, so calls to your numbers reach your agent. |
| Outbound | You give Vio your outbound host (where to send calls). | Vio dials through your carrier when running a campaign or a callback. |
Once the trunk is connected, you attach your DIDs (your phone numbers) to it. An attached DID behaves just like an imported number: assign it an agent, and it’s live.
A normal phone call is narrowband by nature. The public phone network (PSTN) carries voice in a compressed, low-bandwidth format, so a call will never sound studio-HD on the line itself — this is true of every phone call, not a Vio limitation. Your agent still comes through clearly. Recordings stored in your Call logs are captured at higher fidelity than the live phone audio.
Connect a trunk
Open the SIP Trunks view
Select SIP Trunks in the sidebar and create a trunk for your carrier. Remember: one trunk per carrier.
Set up inbound
Vio issues you an inbound host, username, and password. In your carrier or PBX (for example FreePBX), configure a trunk that registers or sends calls to Vio using exactly those credentials. Inbound calls to your numbers now reach Vio.
Set up outbound
Enter your carrier’s outbound host — the address Vio should send outgoing calls to. This lets Vio dial through your carrier for campaigns and callbacks.
Attach your numbers (DIDs)
Attach each DID you want Vio to handle to this trunk. Then assign an agent to each number in the Numbers view — unassigned numbers fall back to your default agent.
Managing a trunk
- Rotate the inbound password. If a credential is exposed or you rotate secrets on a schedule, generate a new inbound password on the trunk and update your carrier to match.
- Detach numbers before deleting. A trunk with DIDs still attached can’t be removed. Detach every number first, then delete the trunk — this prevents accidentally cutting off a live line.
Keep your inbound username and password private. They authenticate calls into Vio; anyone who has them could send calls to your trunk. If you suspect they’ve leaked, rotate the password immediately.
Frequently asked
Q. What does BYOC actually get me over importing Twilio? You keep your existing phone numbers and your carrier’s per-minute rates, and you can front Vio with a PBX you already run (like FreePBX). Twilio import is faster to set up; BYOC gives you continuity and control over telephony costs.
Q. Can one trunk carry both inbound and outbound? Yes. A single trunk handles both directions — inbound via the credentials Vio issues you, outbound via the host you provide. You configure each side once.
Q. How many trunks do I need? One per carrier. If all your numbers are with a single carrier, one trunk is enough. Add another trunk only when you bring a second, separate carrier.
Q. Why won’t Vio let me delete my trunk? Because numbers are still attached to it. Detach the DIDs first, then delete. This guard exists so you don’t accidentally take a live line offline.
Next step
Attached your numbers? Assign agents in Phone numbers, then start dialing with an Outbound campaign.