Mobile operators blocking Skype, Rebtel and other internet voice calling (VoIP) apps could cause more than 18m British smartphone users to switch networks, according to a new survey.
Up to 60% of smartphone users said they were prepared to switch networks if so-called 'over the top' applications, such as those which make VoIP calls.
The survey was carried out on more than 1,000 British phone users by Opinion Matters, and was funded by the VoIP service Rebtel.
The poll said only 8% believed operators had the right to stop users from accessing VoIP on their phones.
Several mobile networks in the UK currently take steps to prevent access to VoIP services.
While the picture of who blocks what is quite complicated - with some operators allowing VoIP services only for certain phones, on certain tariffs - a recent report said across Europe about 20% of users experienced restrictions.
The VoIP industry is understandably keen to make sure this number does not rise, and in its study asked users if they understood why their operator may block such services. According to the survey 71% did not.
Andreas Bernstrom, CEO at Rebtel, said: "We keep a close eye on the factors that prevent us from delivering a fast and quality calling service to our customers.
"Traffic shaping is a much debated topic within the telecommunications industry and it has been brought to the attention of Berec (Body of European Regulators for Electronic Communications) who are investigating this further to understand the extent of traffic management practices and how it affects consumers’ use of services."