T-Mobile Down Detector: https://downdetector.com/status/t-mobile/map/

AT&T Down Detector: https://downdetector.com/status/att/map/

How to use Down Detector: 

(For this example we will be looking at Athens, Ga)

So if you want to check the customer's location for tower outages you will first need to verify their address, once again we will be using Athens for this example.

After Verifying their address, type the address into Google and find it on Google Maps.

Then zoom out to see where at on the map they are,

After doing so open up the Downdector link corresponding with the sim card/plan. 

Now using google maps, locate where at on the map your desired location is.

So as you can see here in this example the desired area has yellow on it. This means there are mild outages in the area.

Yellow/Orange= Mild outages

Red= Severe outages