Skype has 500m users around the world
Egypt has reportedly banned mobile calls made through services such as Skype.
Skype and other operators offering VoIP (voice over internet protocol) services bypass telephone networks in favour of offering free calls via the net.
Egyptian law states that all international calls must pass through state-owned Egypt Telecom.
The ban. reported by various news agencies, does not extend to voice calls made over fixed-line internet.
The ban applies to Egypt's three mobile operators, Vodafone, Mobinil and Etisalat and came into effect at the weekend.
"The National Telecom Regulatory Authority issued a decision to stop VoIP and we stopped it on Saturday," Khaled Hegazy, Vodafone Egypt's external affairs director told AFP.
Skype has 500 million users worldwide.
In a statement the firm said: "In general, we believe it should be up to consumers, not regulatory authorities, to choose the winners and losers in the communications space."
Many mobile operators now offer Skype services, although it is still a relatively small market.
Egypt is not the first country to ban such services. Earlier in the month the United Arab Emirates said it would not give VoIP licenses to international companies such as Skype.