“When you use Signal, your data is stored in encrypted form on your devices. The only information that is stored on the Signal servers for each account is the phone number you registered with, the date and time you joined the service, and the date you last logged on.”
Doesn’t your phone already have a sms app?
Its immensely difficult to convince your circle to download yet another app to message a handful of people. It is much easier to convince them to replace their SMS app.