T-Mobile US Inc. is making video calling available to its customers, its chief technology officer Neville Ray said in a blog post Thursday. “Of course, there are apps that do video calling. But this isn’t another app. T-Mobile Video Calling represents a huge step forward in how Americans make mobile phone calls,” Ray wrote. He said that to make calls, viewers will choose between the voice call and video call buttons on their phones without having to download or install an app. The video calling service “moves seamlessly between LTE and Wi-Fi,” he added. Video calls will count against users' data caps when done on an LTE network, Ray said. Users with Samsung Electronics Co. Ltd.'s Galaxy S6 edge+ and Galaxy Note 5 smartphones can upgrade to video calls now, while software updates for Galaxy S6 and...