Every Clodia deployment starts with the same practical question: how does a phone call get from the public telephone network to the AI? The answer decides who provides the number, what your operator needs to agree to, and how much changes in your office.
Clodia supports three routes, which we call transports. Whichever you use, the conversation, the playbook and the desk your team works from are the same. A call is matched to your business by the number that was dialled, so moving a number from one transport to another does not change how its calls are handled.
1. A Twilio number (the default)
Most businesses start here. The call arrives on a number provided through Twilio, and Twilio streams the audio to Clodia over a secure WebSocket. Clodia bridges that stream to the voice model and sends the voice back the same way.
You can use this route in two ways:
- A new number that you publish for enquiries, bookings or after-hours calls.
- Your existing number, forwarded. You keep your current line and set call forwarding, for example on no answer, when busy or outside opening hours, to your Clodia number. Your operator controls forwarding, and forwarding to an international number may be charged as an international call, so check the tariff first.
Because the audio passes through Clodia, this route also carries features that depend on the audio path, such as the quiet office ambience Clodia can mix under its voice so callers don't hear dead air.
Availability of local numbers differs by country. In some countries, including the UAE, local numbers and voice services are tightly regulated and an international provider may not be able to offer a local number at all. Our UAE SIP trunking guide explains the options there.
2. Your own carrier SIP trunk
Larger organisations often already have a SIP trunk from their operator feeding a phone system (PBX). In that case the carrier or PBX can send calls for chosen numbers straight to the voice model's SIP endpoint. OpenAI publishes one SIP address per project, reached over TLS, and Clodia identifies your business from the number in the call's headers. Nothing on Clodia's side needs configuring beyond registering your number.
What this route needs from you and your operator:
- Permission to route to an international cloud destination. Many business trunks are provisioned on the assumption that calls end at a phone system on your premises. Whether your operator will route calls onwards to a foreign cloud SIP address, and under what conditions, is a question for your operator. In the UAE, put it to e& or du directly and get the answer in writing.
- TLS signalling and a compatible codec. G.711 is the safe common choice for phone audio.
- Caller ID preserved. Ask whether the trunk passes the original caller's number through. If it doesn't, Clodia cannot greet returning callers by name or link the call to their history.
The trade-off: on this route the audio goes directly from your carrier to the model, so features that rely on Clodia handling the audio, such as the office ambience, are not available.
3. A trunk we provide
For businesses that want a number from us but without Twilio in the path, Clodia can run calls over a SIP trunk that we hold with a carrier and point at the voice model. This route is designed in and can be switched on per number, but it depends on a carrier agreement in each country, so ask us about availability where you operate.
Comparing the three
| Twilio number | Your own trunk | Our trunk | |
|---|---|---|---|
| Who provides the number | Clodia, via Twilio | You, via your operator | Clodia, via a carrier |
| Change in your office | None, or call forwarding | Routing on your PBX or trunk | None, or call forwarding |
| Operator conversation | Only for forwarding tariffs | Yes, and get it in writing | Handled by us |
| Office ambience | Yes | No | No |
| Best for | Getting started quickly | Existing enterprise telephony | Where a local carrier route is needed |
What about transferring to a person?
Handing a live call to a member of staff is the most requested feature on any AI phone line, and it is harder than it looks. On a SIP route, a transfer means sending a SIP REFER to your carrier and confirming the new leg actually connected. Developers have reported cases where a transfer request was accepted but never reached the far end. We will not ship a transfer that can claim success without proof. Until live transfer is available on your route, Clodia logs urgent calls for immediate follow-up and tells the caller honestly what happens next.
Choosing a route
If you are trying Clodia for the first time, start with a Twilio number or forward your existing line after hours. You can move a number to your own trunk later without changing the playbook or retraining anything. If your organisation already runs a SIP trunk and a PBX, read our guides to SIP trunking in the UAE and the hardware on site before talking to your operator.
Sources and further reading
Hear Clodia for yourself.
Try a live conversation in your browser, or tell us about your front desk.