SIP trunks explained for people who aren't telecom engineers

If you're evaluating a voice AI platform and someone on the sales call says "just bring your own SIP trunk," here's what that actually means in plain terms, without the telecom jargon.

What a SIP trunk is

Think of it as the pipe that carries your phone calls over the internet instead of old copper phone lines. Your telecom provider issues this connection, and anything that speaks SIP, which stands for Session Initiation Protocol, can plug into it. That includes a voice AI platform like Accordia.

The upside of bringing your own trunk instead of using numbers issued by the platform is that you keep your existing phone numbers, your existing carrier relationship, and your existing pricing. Nothing about your public-facing numbers changes for your customers. They keep dialing the same number they always have.

How routing works once it's connected

Once your trunk is connected, dispatch rules decide what happens to an inbound call. A rule might say calls to this number go to the sales agent, or calls to this number after 6pm go to the after-hours bot, or calls from this area code get routed to a Mandarin-speaking agent by default. You're not stuck with one agent handling every call on every line the way a lot of simpler systems force you into.

For outbound work, the same trunk (or a separate one, depending on your setup) handles calls going out. Number pools let you rotate the outbound caller ID across a campaign, which matters more than people expect. A single number making hundreds of outbound calls a day tends to get flagged by carrier spam filters, and your answer rate quietly craters without anyone noticing why.

What to check before connecting

Confirm your carrier actually supports SIP trunking, which most modern providers do, but it's worth a direct question rather than an assumption. Check your current concurrent call capacity, since this caps how many simultaneous conversations your setup can handle regardless of how good the AI is. And think through whether you need separate number pools for outbound work versus your existing inbound numbers, since mixing them can hurt the reputation of numbers your customers already trust.

Bring your own, or start fresh

Bringing your own trunk is usually the right call if you already have a working phone setup you don't want to disrupt, and your customers are used to calling a specific number. Starting fresh with newly provisioned numbers makes more sense if you're setting up a new line of business from scratch, like a new outbound campaign that never had a dedicated number before.

Either way, this is usually a one-time setup conversation with your telecom provider and takes far less time than most people expect walking in.