It’s simple to add anyone to a group using their phone number or their email address. If they're new to GroupMe, there’s no need to download an app right away. They can start messaging over SMS immediately.
You can even use GroupMe to hold a conference call or conduct polls.
Many organizations such as schools and churches have used GroupMe for communication.
Under the covers, GroupMe is pretty clever. Each GroupMe group is assigned a phone #. This is how the SMS and conference call features work.