Joining a group via Email or SMS (text message) connects the people who have service. When an email or phone is added as a member, a message is sent to them. It includes a link to join the group. When they click on that, it adds the recipient to the group. It also directs the recipient to a web page where they can view group details, messages, and locations. The recipient will still receive email/SMS updates and can respond to the group via the webpage, however those members will not share their locations.