I have used Cel.ly for going on 3 years now. It has been a great tool to communicate with my students. It has lots of great options and their customer service is great. With all that said I have embarked on a different path this year, I have students choosing how to use it.
Classes this year are set up as multinational businesses and they were challenged with communicating with all their employees. Some resided in different class periods so the guidelines were however they choose to communicate it had to be in a way that could be recorded and could be used anytime, anywhere to join the discussion. One group chose Cel.ly.
As I have observed this group they have exemplified what 21st century skills look and feel like. The platform, Cel.ly, allows any device to be connected to the conversation. Students have used iPhones, PC, iPad and Droids to connect. They have discussed issues and concerns from 2 am on a school night through midnight on a weekend. They have shown great collaboration and teamwork.
I still feel Cel.ly is a great tool for teachers and schools but am just realizing it's so much more when you give it to the students.