The Department of Telecom had been asked by the Intelligence Bureau to block the 'We Phone' application as it facilitated spoofing of caller id and was difficult to identify to locate or identify actual caller, PTI reported.
According to an official source, IB had written to DoT about a month back to block We phone application which was freely available on Android Play Store and Apple's application store as it allowed users to spoof calls.
The application which has a call service similar to Skype, allows users to make free calls using mobile internet service to other subscribers having same application.
The application, verifies user's phone number at the time of installation and gives an option to disable the number to hide it.
According to IB, in free version of the application, caller id on the receiver screen started with +1777 while in paid version any number could be set to display as caller id.
According to the Intelligence agency, the server of We Phone was located outside India and any call made from We Phone was routed through the server located abroad which made it very difficult to identify and locate the actual calling number or user.