T-Mobile Wi-Fi Calling App is a Tool For Hackers

T-Mobile devices having a default Wi-Fi Calling feature that keeps you connected in areas with little or no coverage using Wi-Fi connection. But this feature lets millions of Android users vulnerable to Man-in-the-Middle attack. To become a man-in-the-middle would be for the attacker to be on the same open wireless network as the victim, such as at a coffee shop or other public space.

 The flaw could potentially allow hackers to access and modify calls and messages made by T-Mobile users on certain Android smartphones.
T-Mobile uses regular VoIP for Wi-Fi Calling instead of a connection that encrypted, something that aids in its vulnerability. The certificate validation had not been fully implemented, so without this proper verification, hackers could have created a fake certificate and pretend to be the T-Mobile server. T-Mobile released a security update to its Android users on March 18 that resolved the issue.