Auto call and play an audio recorded message

Question

I wish to make automated calls to a list of numbers to then play a recorded audio message to them. The ones that don't pick up get a call back later.

What's the cheapest and easiest way to develop this using some pre-existing tools? Any directions welcome.

Answer 1

Note: You can play back the audio data only to the standard output device. Currently, that is the mobile device speaker or a Bluetooth headset. You cannot play sound files in the conversation audio during a call.

from the official docs

Answer 2

I ended up using automated flow apps (Automate [link below] is one such app that I used. Disclaimer: I've no affiliation with app) to trigger automated calls. The flow was initiate on a GCM notification to the phone, which provided the number for call. With all permissions granted and conditions fulfilling (network, sim, call credits, etc.), app should be able to make call to the number.

Now, I'm trying to figure out how to play an audio message for the receiver. So, if you were looking for 'how' part, here's the how part. If you know the next steps, enlighten me!

https://play.google.com/store/apps/details?id=com.llamalab.automate&hl=en&gl=US