Connect a calendar, set a rule such as “text the customer 24 hours before the appointment”, and reminders go out on their own from then on.

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The four pieces

Set these up in order. Each one depends on the one before it.

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Set up your first reminder

End to end, this takes about ten minutes plus a wait.
The Setup Guide button at the top of the screen opens a reference panel covering how to format appointments in Google Calendar and Office 365, the full variable list, and what the platform does not read. Worth opening alongside these steps the first time.
1

Connect your calendar

Go to the Connections tab and click Connect Google or Connect Office 365. A sign-in window opens.Approve the permission request. The window closes and your connection appears with its email address.
The connection shows status synced. Anything else means it is not being read yet.
2

Add the phone number to your appointments

Reminders are sent to a phone number in the appointment title. Put it there in international format:
No other field is read. A number in the description or a custom field will not be found.
3

Write a template

On the Templates tab, create the wording. Insert variables such as {customer_name} and {appointment_time} using the chips beside the editor, and check the live preview.Keep it under 160 characters to stay within one message part.
4

Create a rule

On the Rules tab, tie it together:
  • which connected calendars it applies to
  • how far ahead to send, in minutes, hours, days or weeks
  • which appointments qualify
  • which template to use
  • whether the rule is active
A common first rule is 24 hours ahead, applied to every appointment.
5

Test it immediately

Use Test on the rule and give it your own number. This sends straight away and skips all the waiting, so it is how you check your wording before trusting it to real customers.
A test is a real text message and costs credits.
6

Wait, then check the Events tab

Allow up to 20 minutes. Then open Events and look for appointments showing a reminder as scheduled.
An appointment showing scheduled with a time means the rule matched and the reminder is queued. That is the confirmation your setup works.

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Allow up to 20 minutes

The most common support enquiry about this feature is that it did not work. In most cases it did, later than expected.
A rule you add now does not apply to your appointments straight away. Heullo re-reads your calendars every 15 minutes and checks for due reminders every 5 minutes, so allow up to 20 minutes before anything visible happens.Never rely on this for a reminder due within the hour. Use Test for anything you need immediately.

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Connections

A connection showing error does not recover on its own. It is skipped by the scheduled read until it is re-established, so reminders silently stop. Disconnect it and connect again.
Sync now forces an immediate read rather than waiting for the next cycle. Useful after adding appointments you want picked up straight away.

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Only the next 30 days are read

Appointments further ahead than 30 days are not read at all, so a reminder cannot be scheduled for them yet. They come into range as the date approaches, and a later read picks them up.
This matters for long lead times. A rule set to remind 6 weeks ahead of an appointment will never fire, because the appointment is not visible to Heullo until 30 days out — by which point 6 weeks ahead has already passed.

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Templates

A template is the wording of the reminder. Variables are replaced with each appointment’s own details when it is sent.

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Available variables

{event_title} inserts the entire title, which includes the customer’s phone number if you have put it there for recipient detection. Use {customer_name} unless you specifically want the raw title.
The editor counts characters against 160 and marks the field once you exceed it. Longer messages still send, as multiple parts, and are charged accordingly. See Message encoding. Templates can be tagged as appointment, reminder, confirmation, cancellation or follow-up, and one can be set as your default. Tags are for your own organisation and do not affect behaviour.
Use the live preview before saving. It renders your template with sample values, so a mistyped variable name is obvious immediately rather than arriving unreplaced in a real reminder.

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Rules

A rule requires a name, a template, and at least one calendar. It cannot be saved without all three. Timing reads as a sentence: send the message a chosen number of minutes, hours, days or weeks before the appointment.
A rule can cover one connected calendar or several, selected individually. If you have connected both a work and a personal calendar, restrict the rule to the one holding customer appointments.
How far ahead to send. Note the 30-day read window above when choosing anything longer than a month.
Which wording to use. The rule editor previews the selected template’s content so you can confirm you have picked the right one.
Turn a rule off without deleting it. Useful for a seasonal reminder, and safer than deleting and rebuilding.
If you have no connections or no templates yet, the rule editor says so directly and points you to the tab you need. Rules genuinely cannot work without both, which is why they are the third of the four pieces rather than the first.
Each rule counts reminders sent and failed. That pair is the fastest diagnosis available: sent zero and failed zero means the rule is not matching anything, while sent zero and failed some means it is matching and failing to deliver.

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Events

Lists the appointments read from your calendars with each reminder’s state.

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Where the phone number comes from

The reminder is sent to a phone number in the appointment title. No contact list is involved, and no other field is used. So an appointment titled:
sends the reminder to +35799123456.
An appointment with no phone number in its title cannot produce a reminder. The Events tab flags these individually, so check there rather than assuming the rule is at fault.
If a booking system creates these appointments for you, check what it writes into the title before building rules. Many systems put the customer’s number in the description or a custom field, neither of which is read.

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Troubleshooting

Check in this order: the connection shows synced, the rule is active, and you have waited 20 minutes. Then check the Events tab — if appointments are listed but none show scheduled, the rule is not matching them.
The rule is not matching. Check the rule covers the right calendar, and that its conditions are not excluding these appointments.
Usually no usable phone number in the appointment, or insufficient credits at the moment the reminder was due. The rule’s failed counter and your transaction history will distinguish the two.
Check the connection status first. A connection that has moved to error stops being read and does not recover by itself.
Greek text is converted to uppercase for delivery. See what you are charged for.

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Step by step, in detail

Not needed for everyday use. This explains the timing above, if a reminder has not arrived and you want to know which stage it is waiting at.