(Telecompaper) Cisco and Italian VoIP provider Messagenet have challenged the European Commission's 2011 approval of Microsoft's USD 8.5 billion acquisition of Skype, saying the EC should not have allowed the creation of a monopoly, Reuters reports. Cisco's attorney, Luis Ortiz Blanco, told judges that the takeover "marked a tipping point in the video communications market". The plaintiffs are arguing that the EC should have forced Microsoft to make concessions for the deal to be approved. Microsoft said in March that it one-third of the world's voice calls are on Skype and over 280 million people use the service for more than 100 minutes each month. EC lawyer Corneliu Hoedlmayr pointed to Skype rivals such as Google Talk and Viber as evidence that there is no competitive harm, adding that emerging technologies "could render Skype a relic". The court is due to give its verdict in the coming months.