Our church currently uses Facebook, Instagram and our homepage to get notifications out to our parishioners. We know about REMIND, but it appears to be cell phones only. Is there anything that would do texts, email and phone calls? As I said, our CHURCH, which means we can't afford very much.
Will offer some initial comments to get things started.
Most email programs (e.g. Outlook) permit you to establish a contact list targeted to a select group of individuals.
So that capability may already exist and will cost nothing to implement per se. Just someone taking the time to create, verify, edit, and maintain the mailing lists. Those lists can often be kept in a separate database or other source location.
Texting and phone calls are likely to be more problematic. Which is why similar groups relay on phone trees for mass notifications.
Another concern is that your service providers may flag the outgoing information as spamming - and block your email account/phone number accordingly.
Any universities or colleges nearby? If so and if they have any sort of IT program you may be able to set up an internship to get some help. Many degree programs require some final "project" by senior level or graduate students to earn their degree.
A project that is supervised by a professor or even a group of professors. They help match up student (or team of students sometimes), client, and project. And at no cost to you. May or may not be viable in the end but worth looking into.
Just my thoughts. There may be other ideas and suggestions offered as well. No problem that...