How do I get my phone to ring on a calendar notification? I'm always missing appointments because the event notifications in Calendar app are so pathetic.

I when its time to leave for an appointment, I want my phone to ring as loud as possible as if I'm getting a phone call, and to continue ringing until I turn it off.

Is there any app/SaaS for this?
There are apps available ( listed at end ) but IMO , automation is the preferred way for this since :


You are looking for conditional actions
Customisation options to suit individual needs


I prefer using Macrodroid automation app because it's free ( upto 5 macros ) and very easy to learn



You would need two macros for this

(Triggers / Actions / Constraints are added by +   on the right side of each panel )

Logic: 


Ring on Calendar Notif Macro :   Whenever you get a notification from your calendar app, alert you with a non - stop ringing , at a volume level and sound customised by you
Stop Ringing Macro :  Manually stop the ringing using a widget on your home screen and set the Volume levels to what you would prefer in your normal device usage


Barebone implementation of this logic is implemented in Macros below. You can customise it later by experimenting






Don't get intimidated by the long explanation - it's detailed so that you don't waste time setting it up ; shouldn't take you more than 5 minutes to set up :)

Ring on Calendar Notif Macro


Trigger: Notification Received &rarr; Select your calendar app  &rarr; Text  &rarr; Any
Actions
Set Macrodroid Variable  &rarr; New Variable  &rarr; Stop Ringing , Type Boolean  &rarr; Set it to false  (initialising variable that controls when to stop / start ringing )
Repeat Actions ( second item on drop down when you press the plus sign on action panel ) &rarr; While condition repeat &rarr; Conditions + &rarr; Macrodroid Variable &rarr; Stop Ringing  &rarr;OK &rarr; Select False and OK


This creates a while / do loop wherein we want you to be sued when notification arrives something to be done when . You see now a WHILE / DO - End Loop created . Tap the End Loop and you will get a pop up Add action above. Tap that and add actions below


Volume Change &rarr; select Media / Music and set slider to say maximum % tap OK 
Play &rarr; select any sound from drop down list
Wait before next action &rarr; set it to 2 seconds 


Constraints: Leave blank

Stop Ringing Macro


Trigger:  Empty Trigger


Actions


Set Macrodroid Variable Stop Ringing to True
Volume Change - set the Volume levels you normally have on your device


Constraints: Leave blank

Go to the widgets section of your launcher , drag and drop Macrodroid widget to your home screen and assign it to Stop Ringing macro

Alternative app option


Calendar event Reminder claims ( not tested by me ) to



  With this simple app you can override or replace default reminder with "unmissable" ones - they will ring like phone call how long you want, with melody you want!



See Izzy's collection of Calendar Alarm Fixes