The short answer
On a phone system, you don't forward a line: you change the route that every incoming call follows. That call flow almost always looks the same: a number, opening hours, possibly an automated phone menu, then a group of extensions that ring, a queue, and finally a destination when nobody answers. It is this last destination, the overflow, that you point to the voice agent's number. The same setting is used out of hours.
Menus have different names depending on the vendor and the model, and we won't name any of them. In your interface, look for words such as “incoming calls”, “routing”, “group”, “queue”, “overflow”, “opening hours” or “external forwarding”.
Three types of equipment, three places to look
| Equipment | Where overflow is set up | Who can do it |
|---|---|---|
| Cloud phone system | The service's online admin portal | The company's administrator account |
| On-premises IP PBX | The server's admin console | The administrator, often the installer or maintenance provider |
| Multi-line internet box/router | The operator's customer area, line by line | The account holder |
Cloud phone system
The setting is made on the main number, or on the group that receives it, in the section for incoming calls. You need administrator rights: an ordinary user can often only see their own forwarding settings.
On-premises IP PBX
Distinguish between forwarding on an extension and the server's call flow. Forwarding set on an extension, on the phone itself, only applies to that extension. Overflow set on the server covers the main number, even when an extension is switched off or unplugged. For a voice agent, it is the server you need to configure.
Multi-line internet box/router
A box that carries several numbers is usually set up line by line, like an ordinary landline. Decide which numbers to forward: first and foremost, the one on your website and your quotes. For French lines, the steps specific to each operator are described in our guides for Orange, Bouygues Telecom and Free, and the common codes in the how-to guide to conditional forwarding.
The four overflow triggers
| Trigger | Without overflow, the caller… | The setting to look for |
|---|---|---|
| Nobody in the group answers | ends up in voicemail | The group's ring time and the no-answer destination |
| All extensions are busy, or the queue is full | hears the engaged tone or waits a long time | Queue capacity, maximum waiting time, destination when the queue is full |
| Out of hours, public holiday, closure | hears the closed message | The time schedule, public holidays, the out-of-hours destination |
| Manual switch | stays on the daytime setting if nobody remembers | “Closed” or “night” mode, if your equipment has one |
For a voice agent, the first three triggers point to the same external number: the agent's. The manual switch completes the set-up for an unplanned closure.
Where to place the agent in the call flow
As overflow, behind the team
This is the agent's natural place in an organisation that already has a reception. The extensions ring first; the agent takes what the team can't. It backs up your teams and never replaces them. The guide to the voice agent and the reception team details how roles are shared. In a medical centre, this stops a patient waiting while reception is already on the phone.
Out of hours only
The team keeps the daytime; the agent takes evenings, weekends and public holidays. This is the simplest setting: a single destination in the time schedule.
As the first point of contact
The agent answers every call and transfers to the team according to your rules. From the Pro plan upwards, Sayelo handles multiple transfers by reason for calling. In that case, the phone system is only used to receive transfers: set it up so that these calls don't overflow back to the agent.
What to check before switching it on
- Permission to call an external number. Some phone systems restrict forwarding to outside numbers. The profile that carries the overflow must be able to call the agent's number.
- Simultaneous channels. On an IP PBX connected to an operator, a call overflowed to an outside number uses one incoming channel and one outgoing channel for its whole duration. If your subscription allows only a few simultaneous calls, overflow will fail precisely at peak time. The peak hours guide helps you estimate this need.
- The number displayed. Check that the phone system passes on the original caller's number, not the company's. Depending on your operator, this may need a specific setting: check with them or with your installer.
- The group's voicemail. If a voicemail kicks in before the overflow, the call never reaches the agent. Remove it, or place the overflow before it.
- The total delay. The caller's wait is the group's ring time, plus the queue, plus any automated menu. Keep that total short.
- Loops. If the agent transfers an emergency to a phone system number that itself overflows to the agent, the call goes round in circles. For transfers, choose a direct line or a mobile.
- Opening hours. Make the phone system's time schedule match the hours the agent knows, including public holidays and closures.
Testing each scenario
| Scenario | How to trigger it | What you should see |
|---|---|---|
| No answer | Call and let all the extensions ring | The agent answers after the set delay |
| All lines busy | Make all the extensions busy, then call | The agent answers without a long wait |
| Out of hours | Call after closing time | The agent answers, with no closed message before it |
| Transfer back | Tell the agent you have an emergency | The call reaches the right extension, without coming back to the agent |
| Number displayed | Read the summary received by email | The number shown is the test phone's |
With Sayelo
Sayelo answers the calls your phone system sends it, announces that it is an AI, books appointments in your calendar, transfers emergencies according to your rules and sends you the summary of every call. Depending on the plan, the agent takes 1, 2, 5 or 10 simultaneous calls: choose according to the number of calls that can overflow at the same time. An accountancy firm in tax season doesn't have the same needs as a sole trader. Our comparison between an AI voice agent and a cloud phone system explains what each one does, and why they work well together. Plans are detailed on the pricing page.
