The Egyptian communication is used to keep people from politics, work and making money. External telephony is carried out exclusively via the Telecom Egypt (TE) network. The state is the largest shareholder in Telecom Egypt. It thus blocks foreign communication as well as possible. Viber, Kik, IMO, Facebook Messenger, WhatsApp and line are mostly not used for business communication abroad and are available because it does not affect the state: domestic telephony is handled by private providers. Skype audio and video were blocked for mobile networks many years ago, after their share of foreign telephony exceeded 15%. The same applies to all VoIP providers using the SIP protocol. VPN also does not really help: most of the ports usually used for VoIP have been closed successfully by Egyptian Telecom.

Usually, Skype can still be used in the DSL network. However, today (2017-06-28) even this was impossible for reasons I do not know.