Skip to main content
Audience: whoever administers your phone number or hosted PBX. Time: 5 to 10 minutes. Works with: any carrier or hosted platform that can forward a number, including RingCentral, 8x8, GoTo, Dialpad, and traditional telco lines.

​
What it is

DID forwarding is the simplest way to put the AI on a phone number. Instead of connecting a SIP trunk between your phone system and SmartAlex, you keep your number exactly where it lives today and set it to forward to a SmartAlex number. A DID is just a phone number (the industry term is Direct Inward Dialling). When a caller dials your published number, your carrier or hosted PBX immediately forwards the call to the SmartAlex number behind it, and the voice engine answers. Your callers never see the forwarding number. They dial the number on your website and the AI picks up. Nothing about your account with your carrier or PBX changes. You are using the same call-forwarding feature you would use to send calls to a mobile or an answering service, pointed at us instead.

​
When to use it

Hosted PBX platforms

Cloud phone systems like RingCentral, 8x8, GoTo, and Dialpad do not always expose a generic outbound SIP trunk on every plan. Every one of them can forward a number, so DID forwarding works no matter which plan you are on.

A quick start or pilot

You want the AI answering a real number this afternoon without touching PBX config, opening firewall ports, or filing a support ticket with your carrier. Forward the number, test, done. You can graduate to a SIP trunk later.

Overflow and after-hours

Forward a number only when your team is closed, or only when a queue overflows, and let the AI catch what would otherwise hit voicemail. Your PBX decides when to forward.

No PBX at all

You have a plain telco number with no phone system behind it. Set conditional or unconditional forwarding in your carrier portal and the AI answers.

​
How it compares to a SIP trunk

Both approaches get the AI answering your calls. They differ in where the wiring lives and how much control you keep.
The one thing to check up front is caller ID passthrough. When a call is forwarded, some carriers and hosted PBXes pass the original caller’s number through and some replace it with the forwarding line’s number. If your agent needs the real caller ID (for lookups, logging, or callbacks), confirm your platform forwards the original CLI, or move to a SIP trunk where caller ID is preserved end to end.

​
The flow

Because there is no trunk back into your phone system, a transfer to a human is the voice engine placing a fresh outbound call to a phone number (a mobile, or an extension reachable on a public DID) and bridging the caller to it. If you need transfers to ring an internal extension directly over SIP, use a SIP trunk instead.

​
Setup outline

1

Provision a SmartAlex number

In the dashboard, go to Phone Numbers, then Buy Number (or Import Your Number if you already own one you want us to host). Pick the country and area code, and assign it to the agent that should answer. This is the number you will forward to. It stays private, your callers never dial it directly.
2

Turn on forwarding at your carrier or PBX

In your carrier portal or hosted PBX admin, find the number your customers actually dial and set its call-forwarding destination to the SmartAlex number from step 1.
  • Plain telco number: set unconditional (or conditional) call forwarding to the SmartAlex number.
  • Hosted PBX, single user or number: open the user or number, then Call Handling and Forwarding, and forward to the SmartAlex number.
  • Hosted PBX, queue or auto-attendant: set the overflow, no-answer, or after-hours destination to the SmartAlex number so the AI catches those calls.
3

Add transfer contacts in SmartAlex (optional)

If the AI should be able to hand callers to a human, open the agent and add the people or departments it can reach, each as a reachable phone number (a direct dial, a mobile, or an extension exposed on a public DID). Give each a display name and free-form aliases so the AI matches a request like “put me through to accounts” without you scripting every phrasing.
4

Link the agent

In Agent Studio, open your agent, go to the Telephony tab, and confirm the SmartAlex number is assigned to it. Save. The next inbound call will reach this agent.
5

Test the number

From a mobile, dial your published number (not the SmartAlex one). Your carrier forwards it, and the AI should answer within a second or two. If you configured transfers, ask to be put through and confirm the target rings.

​
Things to know

No. Callers dial your published number and hear the AI answer. The SmartAlex number sits behind the forward and is never shown to them.
Yes. Forwarded calls show in your carrier or PBX records as forwarded to an external number, exactly like forwarding to a mobile. SmartAlex keeps its own detailed call records with transcript, outcome, and recording independent of your platform.
Yes, and this is a common setup. Use your platform’s conditional forwarding: after hours, on no answer, or on queue overflow. The AI only picks up the calls you route to it, and everything else stays on your normal routing.
Your forwarding line’s capacity governs how many calls can be forwarded at once. If you expect high concurrency, confirm your carrier or PBX allows enough simultaneous forwarded legs, or move to a SIP trunk where you set the concurrent-call limit explicitly.
Yes. DID forwarding and SIP trunks coexist on the same account. A common path is to start with forwarding for a pilot, then move the number onto a trunk once you want caller ID preserved end to end and transfers handed straight back to your PBX. Nothing you set up here is wasted.

​
Next steps

Connection modes

Compare DID forwarding, inbound SIP trunk, and native extension mode, and pick the right one.

RingCentral

The full forwarding walkthrough for a RingCentral account.

Troubleshooting

If the forward does not reach the AI, start here.