Make outbound calls and answer incoming calls

Phone calls use three steps. Incoming voice call is a trigger in the Triggers group of the Nodes panel: it starts the agent when someone rings your organisation's voice number. Outbound call, in the General group, rings one number each time a run reaches it. Voice AI, in the AI group, is the voice on the line in both cases. It follows your instructions, talks to the person, and can use tools while it talks.

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Confirm tomorrow's visits

1,240 / 10,000 creditsValidateReset

Runs6

SettingsUpdate & Publish

Weekdays at 16:00

Daily at 16:00 · Mon, Tue, Wed, Thu, Fri

Tomorrow's visits

List jobs

Has a phone number

personMobile is not empty

Visit confirmer

You are an automated assistant ringing Harbour FM customers about visits booked for tomorrow.

4

Each visit

Batch size 1

Confirm the visit

Rings {{ item.json.personMobile }}

5

Answered by a person

answeredBy equals person

Note the answer

Create note

AI builderMap

1. 1Incoming voice call, the trigger for a phone line, in Triggers.
2. 2Voice AI, the voice on every call, in AI.
3. 3Outbound call, which rings someone during a run, in General.
4. 4The Voice AI that talks on this call, above it on the dashed speaker line.
5. 5The Outbound call. Its summary shows who it rings.
6. 6Runs, where every call's transcript and recording are kept.

The figures follow two agents at Harbour FM. Confirm tomorrow's visits runs at 16:00 every weekday, fetches tomorrow's visits from BigChange, rings each customer to confirm the time and writes the answer on the job as a note. Engineer job line answers a number that Harbour FM's engineers ring after a visit to report progress. BigChange stays the job system in both: the agents read jobs from it and write notes back.

A Voice AI never works alone and never sits in the main line of steps. It always pairs with one of the other two.

• On a phone line, Incoming voice call connects straight to a Voice AI. When you add the trigger to the canvas, a connected Voice AI appears beside it and is selected, ready for its instructions.
• On an outbound call, the Voice AI sits directly above the Outbound call, joined by a dashed violet line from the top of the call. This is the speaker line. Adding an Outbound call places its Voice AI for you, and deleting the call deletes its Voice AI and any tools attached to it. Every Outbound call has its own Voice AI.

An agent that answers calls

Find the job

Get job

Engineer job line

Rings +442079460183

1

Take the job update

You are the Harbour FM job line, an automated assistant. Engineers ring you to report progress on a job. Ask for the job reference and read back the site name to confirm it. Then take the update: work done, parts used, and whether the job is complete. Speak plainly and keep replies short.

2

An agent that makes calls

Visit confirmer

You are an automated assistant ringing Harbour FM customers about visits booked for tomorrow.

4

Each visit

Batch size 1

Confirm the visit

Rings {{ item.json.personMobile }}

3

iIncoming voice call and Outbound call cannot share one automation. Put outbound ringing in its own workflow.5

1. 1Incoming voice call, connected straight to its Voice AI.
2. 2The Voice AI that answers, with a tool attached to its top.
3. 3Outbound call, fed by the step before it like any other step.
4. 4The Voice AI that speaks on the call, on the speaker line above it.
5. 5The message you see if you try to put both kinds of call in one agent.

Two rules follow. First, an agent cannot have both an Incoming voice call and an Outbound call. If a caller on your phone line needs ringing back, have the Voice AI record the request with a tool, such as a note on the job, and build a separate agent that finds those requests and rings.

Second, you do not add a Voice AI to an outbound agent yourself. Dragging one in selects the existing one and shows Each Outbound call already has its Voice AI above it. Edit the speaker there. On a phone line nothing runs after the Voice AI, so anything that should happen during the call, such as writing a note, is a tool attached to it (see tools).

Calls use two separate numbers. Both belong to your organisation rather than to one agent.

• The voice number is the number people ring. Claim it on the Incoming voice call, under Number, in Voice number.
• The outbound number is the caller ID people see when your agent rings them. Claim it on any Outbound call, under Number, in Outbound number. Its help text reads One outbound number per organisation. This is the caller ID. It is not the inbound line.

Until a number is claimed, the field is a menu reading Claim a voice number or Claim an outbound number. Choosing a number from it claims it straight away, with no confirmation, and it then shows on every Incoming voice call or Outbound call in your organisation. The builder has no option to change or release a number afterwards, so agree with your team which one to take.

Anyone with Agent access can claim a number while editing an agent: it is not limited to admins. If your organisation wants one person to choose, tell the people who build agents.

These numbers are separate from the mobile number that Send SMS texts from, which is covered in Send text messages.

An agent that answers calls is a phone line: an Incoming voice call, a Voice AI, and any tools the Voice AI needs. Your organisation can have one published phone line at a time.

1. 1Start a new agent and drag Incoming voice call from the Triggers group onto the canvas. A Voice AI appears beside it, already connected.
2. 2Click the trigger and claim your voice number under Number, if your organisation has not already.
3. 3Choose whether to record calls and who can get through, both described below.
4. 4Click the Voice AI and write its instructions, as in Set up the Voice AI.
5. 5Attach any tools it needs, try it with Run now, then click Save and Publish.

Record the call stores an MP3 of every call for 30 days, then deletes it. Each stored recording costs 1 extra automation credit, and the switch reaches the live line the next time you publish. Callers are told: if your greeting does not mention recording, the call starts with This call is recorded. before it, and if there is no greeting, the Voice AI is told to say so in its first sentence.

Access appears once a number is claimed. Gated is the setting to start with: only the numbers in Approved inbound numbers are connected, and the help text warns that An empty list connects nobody. Open connects any caller, and keeps the list without using it. Type numbers as 07… or +44…, then click Save. The toast Inbound access saved confirms it, and the change applies to the live line straight away, without publishing again. Switching between Gated and Open also waits for Save.

Leave the line Gated unless you mean it to be public. An Open line answers anyone who finds the number, and every connected minute costs credits.

What a caller hears depends on the state of the line.

This number is not available. plays when there is no published phone line, when your organisation has run out of automation credits or of chat message allowance for the month, or when three calls are already live. Pausing the agent, or moving it back to draft, stops Centrus answering the number.

The Voice AI holds everything about how the agent speaks, in one box called Spoken assistant. The settings are the same whether it answers a phone line or speaks on an Outbound call.

• System prompt is required; publishing stops with Voice AI needs a system prompt. without it. Write it as you would brief a new member of staff: who they are, who rings or who they are ringing, what to ask for and what not to promise. Say that it is an automated assistant. On an outbound call, keep the prompt to what is the same on every call and put what changes from person to person in the call's Brief.
• Tool usage says when and how to use each tool you attach, by the name you gave it. A good habit is to have the assistant read back anything it has just written, such as a job note, before moving on.
• Delegation policy decides when the assistant stops talking and uses a tool to check or do something. Left empty, Centrus writes it from the attached tools, which suits most agents. Write your own only if a test shows the assistant hesitating to look things up, or looking things up when it should simply answer. The placeholder shows the format: the tools, when to use them, and when not to. Ending the call and recording the outcome are always included.
• Greeting is said word for word as soon as an incoming call connects. Leave it empty and the assistant opens in its own words. On an outbound call the Greeting is not used: the Opening on the Outbound call is said instead, and the help text under Greeting says so.
• Voice sets how the assistant sounds. Vesper · British is selected to start with and marked RECOMMENDED. The others have Australian, Irish, North American, Brazilian Portuguese, Filipino and Southern U.S. accents, in feminine and masculine voices.

Every call is in British English. The Voice AI is told to speak British English and keep each reply to one or two short sentences, and there is no setting for another language. Choosing a voice changes how the assistant sounds, not the language it speaks.

The Voice AI ends the call itself when the caller says goodbye or asks to finish, when the task is done, or when it cannot help, and the reason is kept with the call. It cannot pass a caller to a person: there is no transfer step. When someone needs a person, have the assistant say who will ring back, and use a tool to record the request or text the right person.

Tools are steps connected to the top of the Voice AI on a dashed violet line, outside the main line of steps. The assistant uses them while it talks: it says it is checking, uses the tool, and carries on with the answer. A Voice AI can use these:

• File Search searches your files in Train, limited to the tags you choose. Use it for manuals, price lists and procedures.
• Web Search looks something up on the web.
• Integration steps, such as BigChange REST, Simpro, JobLogic, Outlook or Microsoft Excel, read and write records in your systems. Set each one up as you normally would, and name it for what it does, because the assistant sees the name.
• Send SMS texts during the call. Leave To blank and it texts the person on the line, for example to confirm what was agreed. See Send text messages.

Site manuals

2 tags

Searches your Train files

Find the job

Get job

Looks up the job

Add a job note

Create note

Writes a note on the job

Engineer job line

Rings +442079460183

Take the job update

You are the Harbour FM job line, an automated assistant. Engineers ring you to report progress on a job. Ask for the job reference and read back the site name to confirm it. Then take the update: work done, parts used, and whether the job is complete. Speak plainly and keep replies short.

Uses them while it talks

Example: an engineer job line. Harbour FM gives its engineers one number to ring after each visit. The line is Gated to the engineers' mobiles and records every call. The Voice AI asks for the job reference, uses Find the job to read the job back from BigChange, takes the update, and writes it to the job with Add a job note. If an engineer asks about equipment on site, it searches the manuals in Train. The office reads the notes in BigChange as usual, and the transcript and recording of every call are in Runs.

A tool on a Voice AI cannot wait for someone to approve it, because the caller is waiting. If one is set to need approval, publishing stops with A phone call cannot pause for approval. Turn off require approval on this tool, or move the write to a step after the call behind Approval. On an outbound call you can do the second: put the write after the call, behind an Approval step. On a phone line nothing runs after the call, so turn approval off or leave that write out.

An Outbound call rings one number each time a run reaches it, hands the conversation to the Voice AI above it, and waits. The run pauses on the step until the call ends, then carries on with what was said.

1. 1Drag Outbound call from the General group onto the canvas and connect the step before it. Its Voice AI appears above it. The call's summary reads Set who to ring until To is filled in.
2. 2Click the call and claim your outbound number under Number, if your organisation has not already.
3. 3Fill in To and Brief, and Opening if you want to choose the first words.
4. 4Click the Voice AI above and write its System prompt, as in Set up the Voice AI.
5. 5Add Result fields for anything you need back from the call, as in What a call sends back.

• To takes a UK mobile or landline: a number starting 07, 01, 02, 03 or 08, with or without +44. Type a fixed number, or a reference such as {{ item.json.personMobile }} to ring a number from an earlier step. There is no From field: every call shows your outbound number.
• Brief is the purpose of this one call, filled in for each person: the visit, the time, the job reference and what to ask. It goes to the Voice AI, not to the person. Keep the standing instructions in the Voice AI's System prompt rather than repeating them here.
• Opening is said word for word when the person answers. Leave it empty and the assistant opens from the brief in its own words.
• iPhone screening is for iPhones that answer unknown numbers by asking who is calling before they ring. Left blank, the assistant gives its name and a one-sentence summary of the brief and the opening. Write a line to have it say that instead.
• If voicemail answers starts as Hang up, which keeps the cost down. Say the opening, then hang up leaves the Opening as a message of up to 20 seconds. If Opening is empty, the Brief itself is read out as the message, so always write an Opening when you choose this. Either way, the call comes back with answeredBy set to voicemail and the result fields empty.
• Record the call works as it does on a phone line, but applies from the next run after you save, without publishing again. When it is on and the Opening does not mention recording, the call starts with This call is recorded.

The phone rings for up to 60 seconds before the call counts as not answered, and a call is ended if it reaches 30 minutes. To ring a list, put the call inside a Loop with a batch size of 1, so it rings one person each time round. The builder warns you if the call is connected to the Loop's Done output instead of its body, or if a step before it passes on several people with no Loop in between.

Your organisation can have three calls live at once, counting phone line calls and browser previews. When all three are in use, the step waits and tries again within a few minutes, up to 30 times. Its summary reads Every outbound line is busy. Trying again within a few minutes (1/30). with the count going up each time.

When the call ends, the step passes on the row it was given with the call's details added. Every call adds seven fields, whoever hangs up first:

• callStatus: completed, no_answer, busy, timeout, voicemail or failed. A dry run gives dry_run.
• answeredBy: person, voicemail or none.
• outcomeSummary: a paragraph on what was said, empty if nobody answered.
• durationS: the connected time in seconds, empty if the call never connected.
• calledAt: when the call was placed.
• closeReason: how the call ended, such as caller_hangup, assistant_end_call, voicemail, no_answer or busy. call_cap means it reached 30 minutes.
• endCallReason: why the assistant ended it: caller_goodbye, caller_asked, task_complete or cannot_help.

Result fields are the answers you need from the call, in a form later steps can use.

• Give each field a camelCase name, such as confirmed or preferredTime, and a type: String, Number, Boolean, Array or Object.
• Use the description to say exactly what you want and in what format, such as a time as HH:mm. The assistant records the answers before it ends the call.
• The seven names above are reserved, and publishing stops if you use one. A name that matches a field already on the row is allowed, but the call's answer replaces the original; publishing warns you so you can rename one of them.

If nobody answers, or the call ends before the assistant has the answers, the result fields come back empty: blank text, no number, an empty list, or false for a Boolean. So a confirmed of false does not mean the customer said no. Check answeredBy first.

The step after the call runs whatever happened. A call that fails does not stop the run, so a Loop moves on to the next person. Use a Condition on answeredBy equals person to act only on real conversations, and connect its false path back to the Loop. Or write callStatus and answeredBy into your own record to log every attempt. Nothing is retried automatically; to try again later, filter on callStatus into a Backoff step and back to the Loop.

{
  "handles": { "main": 1 },
  "items": {
    "main": [
      {
        "jobRef": "J-48213",
        "contactName": "Riverside House",
        "personMobile": "07700 900731",
        "resourceName": "Dylan Hughes",
        "callStatus": "completed",
        "calledAt": "2026-10-09T15:02:11.000Z",
        "durationS": 74,
        "closeReason": "assistant_end_call",
        "endCallReason": "task_complete",
        "answeredBy": "person",
        "outcomeSummary": "Sarah Price confirmed the visit at 09:30 tomorrow and asked the engineer to use the side entrance.",
        "confirmed": true,
        "preferredTime": ""
      }
    ]
  },
  "summary": "Outbound call finished"
}

Later steps read these like any other field, for example {{ item.json.outcomeSummary }} in a job note, or {{ item.json.preferredTime }} in an email to the office.

Confirm tomorrow's visits. This is the agent in the first figure. A Schedule runs at 16:00 on weekdays. BigChange REST with List jobs fetches tomorrow's visits, a Filter keeps those with a phone number, and a Loop with a batch size of 1 runs the call once for each. The call rings {{ item.json.personMobile }} with a brief naming the site, time, job and engineer, and returns confirmed and preferredTime. A Condition checks that a person answered, then BigChange REST with Create note adds the outcome summary to the job, so the office can see in BigChange who confirmed and who wants a different time.

Ring the on-call engineer. When an urgent job comes in out of hours, the agent rings the engineer on call rather than waiting for someone to notice it.

Text the job details

To the person on the call

3

On-call caller

You ring Harbour FM's on-call engineer about urgent jobs.

2

Urgent job logged

Job created

Fetch the job

Get job

Ring the on-call engineer

Rings 07700 900587

1

Tell the duty manager

Send email

4

1. 1The call, ringing the on-call engineer's mobile.
2. 2The Voice AI, with a prompt written for urgent jobs.
3. 3Send SMS as a tool, to text the job details during the call.
4. 4Outlook after the call, emailing the outcome to the duty manager.

A BigChange webhook for new jobs starts the run, and BigChange REST with Get job fetches the details; add a Condition before the call if only some jobs count as urgent. The call rings the on-call engineer's fixed number, with a brief giving the site, the customer and the fault, and asks whether they can attend and when. Result fields canAttend and eta come back, and the Outlook step emails them, with the outcome summary, to the duty manager. If the engineer asks for the details in writing, the Voice AI texts them during the call.

There are two ways to test. A browser preview lets you talk to the Voice AI through your computer's microphone, without ringing any phone. A dry run checks the rest of an outbound agent without placing a call.

On a phone line, open Runs and click Run now. It always starts the preview, and the Runs window says so: Select a call to read it. Run now starts a browser preview and does not ring the phone number. On an outbound agent, select the Voice AI first and then click Run now. With the call or any other step selected, Run now runs the agent and rings real people.

Your browser asks to use the microphone the first time. The word under the circle shows what the assistant is doing: Connecting, Listening, Checking manuals while it uses a tool, Speaking, or Muted. If it shows Could not start voice, check that the browser can use your microphone and try again.

On an outbound agent the preview has no brief, so it tests the Voice AI's own instructions, voice and tools. Tools run for real in a preview, so a tool that writes, such as Add a job note, writes to your system. Send SMS sends nothing. A preview is charged like a call, and counts as one of your three live calls while it runs.

A full run of an outbound agent rings real people. Until you are happy with it, use a dry run, or point To at your own mobile and run it for real once.

In the Run workflow window, Dry run (no actions performed) runs the earlier steps for real, then the Outbound call returns straight away without ringing.

{
  "handles": { "main": 1 },
  "items": {
    "main": [
      {
        "jobRef": "J-48213",
        "contactName": "Riverside House",
        "personMobile": "07700 900731",
        "callStatus": "dry_run",
        "calledAt": "2026-10-09T09:12:04.000Z",
        "durationS": null,
        "closeReason": "",
        "endCallReason": "",
        "answeredBy": "none",
        "outcomeSummary": "Dry run. No call was placed.",
        "confirmed": false,
        "preferredTime": ""
      }
    ]
  },
  "summary": "DRY RUN: outbound call was not placed"
}

Steps after the call run with those empty answers, so a Condition on answeredBy sends a dry run down its false path. Test an agent before it goes live covers dry runs in more detail.

On a phone line, the Runs window lists calls instead of runs. Each shows Phone for a real call or Preview for a browser test, with its credits, when it started and how long it lasted. A caller turned away by a Gated line shows as Phone · Not approved.

Transcript shows what each side said, as Assistant and Caller, with each tool use in between. Thread shows the conversation as the assistant handled it. Call recording plays the MP3 and says Kept until the date it will be deleted. While the recording is being stored it reads The recording is still processing. and after 30 days This recording was deleted after 30 days. The transcript is kept.

For an outbound agent, open the run as usual and expand the Outbound call step. Under Call and the number rung are the recording, if the call was recorded, and the transcript, then the step output (see What a call sends back). A step that did not ring shows No call was placed on this step. Read the Runs panel covers the rest of the Runs window.

Calls are paid for in automation credits from your organisation's monthly allowance. A phone line costs nothing while it waits for calls.

• 1 credit for each started minute of connected time. A call of up to 60 seconds costs 1 credit, and 61 seconds costs 2.
• 0.1 credits each time the Voice AI uses a tool, apart from Send SMS and ending the call.
• 1 credit for each recording that is stored.

A call that is not answered, is busy or is turned away costs nothing. A call answered by voicemail does cost, because it connects, so Hang up usually keeps it to 1 credit. Browser previews are charged in the same way as calls.

On an outbound agent, call minutes are charged to your organisation directly rather than to the run. They are not in the run's credits and do not count towards the agent's Per-run credit budget; the run and its other steps are charged as usual. If you ring 20 customers and 12 of them talk for about a minute and a half, the calls cost about 24 credits, plus 1 for each voicemail.

Calls also need your organisation to have chat message allowance left this month. Calls do not use it up, but once it has run out, outbound calls do not go out and callers to the phone line hear This number is not available. Automation credits and usage limits covers your allowance and where to see what has been used.

These are practical points, not legal advice. Check your own obligations, for example under UK GDPR and the rules on unwanted calls, with whoever advises your organisation.

• Say it is an automated assistant. Centrus does not announce this for you. Put it in the Greeting on a phone line and in the Opening on an outbound call, and in the System prompt so the assistant confirms it if asked.
• Say when a call is recorded. Centrus adds This call is recorded. when your greeting or opening does not mention it, but your own words read better. Cover recordings and how long you keep them in your privacy notice.
• Ring people who expect to hear from you. Outbound calls are for operational calls about work people have booked or are doing, such as visits, jobs and call-outs, not for sales.
• Ring at sensible times. An Outbound call has no calling hours of its own. The trigger decides when calls go out, so schedule them during the day.
• Give people a way to reach a person. The Voice AI cannot transfer a call, so have it give a number to ring, or text one.
• Keep the line Gated unless it is meant for the public.
• Pass only what the call needs. The brief and the row being rung are given to the assistant, so leave out personal details it does not need.

Most problems show up when you validate or publish. A problem during a run does not fail the Outbound call step: the step finishes with callStatus set to failed and the reason in the step summary and outcomeSummary.

• Voice AI must hang above an Outbound call on the speaker handle, or sit on an Incoming voice call. means a Voice AI is left on the canvas with nothing to speak for. Delete it, or connect it.
• Intelligence is not the spoken model on a voice line. Use Voice AI. means an Intelligence step is connected where the Voice AI should be.
• A phone line uses the agent connection. There is no chat user on an inbound call. means the agent's Integration mode is Per-user. Change it to Agent-level in the agent's settings.
• Outbound call timed out, with The call did not finish in time., means the step stopped waiting for the call to come back. The run carries on.
• The call could not be placed. means the call did not start for another reason. Try again, and contact Centrus support if it keeps happening.

To see what a call cost and said, use the Runs window as in Read transcripts and play recordings. To change when calls go out, change the trigger, as in Choose how an agent starts.