SMS reminders should go out each day for the following days appointments. Sometimes though your reception computer may be switched off and they don't send out. This is usually due to a public holiday.
This quick set of instructions shows you how to send appointment reminders that haven't sent.
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Load up the appointment reminder workflow. Note that this will be named whatever it was called when it was created. Mine is called "Daily SMS Reminder". Yours may be named something slightly different.
Change the day the messages are sending for. This step is important. If the messages for today have not sent. Change it to "Today". If tomorrow's messages haven't sent, change it to "Next Business Day". Simply work out which setting you need at this step to send the correct day's appointment reminders.
Now we can send the messages. When you're happy you have the correct day ready, simply press the Go! button on the bottom right of the screen.