cannot watch FOX sports (World Cup) on smart phone even though I am signed on to U-verse.

Hello @yotika!

We'd love to help you here! Are you getting an error message? If so, what is the message? Have you tried using another device, like a laptop? How long has this been happening? Looking forward to your response.

Yetty, AT&T Community Specialist

Use the Fox sports go app along with your Uverse credentials.

If streaming over cellular, then yes using the Uverse app is the way to go.  Going forward, this will become more difficult because networks like Fox are typically not available for viewing live stream, so using the FSG app over WiFi will likely be the only viable solution unless you're on an unlimited plan.