Send SMS from your spreadsheets.
The Sheet SMS add-on allow you to synchronize messages from a spreadsheet and to send them using your mobile phone carrier.
Your phone works as a relay and you can send all the SMS you want.
How to use it : https://youtu.be/7yM8h9tIVs8
The add-on to install on your spreadsheet : https://gsuite.google.com/marketplace/app/sheet_sms/365372815434
More information : https://sheetsms.com/