How can I send an SMS for a form submission?

I’m creating a landing page for an app I’m having built and want site visitors to be able to sign up for a waitlist. They’ll do this by entering their name and phone number into a form on the site and clicking submit, and then I want to be able to send out a mass text to all the numbers that have signed up once the app comes out with a link. Is there a service I can do this for free? I thought Zapier would work, but SMS by Zapier only sends a text to your phone number when a form is submitted, and all the other Zapier apps cost money to send SMS messages.

@christiannc you look into sendgrid by twilio to accomplish that. You’ll need custom code or a zapier integration.