Your group gets its own number. Anyone texts it, replies YES, and every message reaches everyone. Plain SMS, nothing to install.
Or the organizer adds you because you asked. Either way you get one text:
Nobody is in without saying so. You get one confirmation:
In a chat group, everyone sees it. STOP leaves, HELP helps.
Save it as a contact. Every text to it goes to the whole group. No threads to untangle.
Nobody is added without agreeing. STOP leaves. HELP helps. NAME sets your name.
Open chat or announcements only. A daily cap. Quiet hours. A Shabbos hold.
Members pay nothing. The group owner loads a balance and pays only for texts sent. Smartphone members can read the group in the app instead, free.
Every message is plain SMS, one segment, no links required, no pictures required. Members who do have a smartphone can join by link, get notifications, and cost the group nothing.