A major cellphone provider has decided it’s not worth the effort of trying to block subscribers from making calls via VOIP services such as Skype. Instead it’s launching its own VOIP service.

Telefonica, which offers services in Europe and South America, has dubbed the service TU Me. It’s available initially as an iPhone app with an Android version to follow.

Telefonica owns three cellphone companies: Europe’s O2, South America’s movistar and Brazil’s Vivo, covering around 300 million people. However, the app will work for all smartphone owners, even those on rival networks.

As with Skype, messages and calls made through the app will count towards data allowances rather than text limits or call plan minutes. The service will thus be completely free of charge when used via Wi-Fi, though there are (unspecified) daily fair-use limits.

Users can also send pictures and audio messages as well as sharing location details. All message exchanges are backed up online and accessible by users for one year even if they lose or change devices.

The big difference is that users can only call other people who have the app installed rather than non-users or people on landlines. As with most such services, there’s a tool to search for existing phone contacts to see if they have already installed the app themselves.

It seems the service has come about because Telefonica believes there’s no serious prospect of seeing off the likes of Skype. One analyst told the BBC that because the Tu Me service is linked to a user’s specific number, it may deter people from changing networks.