I can send SMS to up to nine other people in a group with an iPhone. They will not get it if not in cell phone reception range. Any group of 11 or more requires

I can send SMS to up to nine other people in a group with an iPhone. They will not get it if not in cell phone reception range. Any group of 11 or more requires all users to be on iMessage. My group is more than ten people, and we work in a hospital (large building with heavy concrete structure - cell reception is entirely absent from significant areas, and we often depend on iMessage over the WiFi for delivering information). Any alternative solution (Signal, GroupMe, whatever) would have to be installed by all. Before I switched to an iPhone, I was one of two out of about 30 who didn't have one. This meant that group messages simply didn't get to me, and I discovered (e.g.) that our secretary had cancer when she asked me about good restaurants near M.D. Anderson. This is bad behavior by Apple, but I decided to be practical about it: I can either be included in important information by buying an iPhone, or I can try to change almost 30 other people who want to keep on using one app for all their text-ish communications. You don't have an option like you do on Android to use Signal, which will send over their own protocol if possible but will revert to SMS for non-users. And, as others have noted, you don't have RCS. But I'm not going to change Apple singlehandedly, and I'm unlikely to force everyone else to use a different app solely to talk to me and one other guy. They'll just keep doing what they've been doing, and we will continue to be out of the loop. Oh, and hospital IT blocks WiFi calling (but not texts). So far, my workaround has been to set up OpenVPN inside my home network and just VPN my entire phone and iPad through that. It takes a few seconds to connect properly, but it does work.