Text messaging is a great way to communicate with parents.  You can use these messaging services to send out urgent messages and reminders.  

• Class Messenger

  You can send messages to parents and students - whole group or individual basis.  You can send picture messages.  

  https://my.classmessenger.com/signup

• ClassDojo Messenger

  Messages can be sent to individuals or an entire group.  Parent do have to opt-in to receive messages.

  https://classdojo.com/messenger

• ClassTag

  You can email SMS/text messages to parents.  This service does track whether or not they are opened and read by parents.  

  http://classtag.com

• Remind

  Students and parents can sign up to receive text messages on their mobile devices.  You can attach files and create groups.  Formerly know as Remind 101.

  http://remind.com

• SeeSaw Messages

  Messaging is a new feature added to this digital portfolio service.  

  https://web.seesaw.me/seesaw-for-schools/