1. Google (2017) Google Hangout.
https://hangouts.google.com/
. Accessed: 2017-05
2. Facebook (2017) Facebook Messenger.
https://www.messenger.com/
. Accessed: 2017-05
3. WhatsApp (2017) WhatsApp Messenger and Collaboration Tool.
https://www.whatsapp.com
. Accessed: 2017-05
4. Microsoft (2017) Enterprise capabilities with Skype for Business in Office 365.
http://products.office.com/en-us/skype-for-business/online-meetings
. Accessed: 2017-05
5. Cisco (2017) Cisco Hosted Collaboration Solution (HCS).
http://www.cisco.com/web/solutions/hcs/index.html
. Accessed: 2017-05