Is it possible for the "reception bars" to be incorrect?

[AC Question]

My father went to a TMobile store 4 or 5 days ago and set up a tablet data plan. The tablet I got him was supposed to arrive the next day but it ended up taking longer. The tablet arrived today but some how he had misplaced the activated sim card they had given him so he went back to the TMobile store to get another one which they did. The TMobile employees did not test the sim card in the tablet but put it in for him and said it was good to go. So later he gets home and calls me on how to use it and I guide him to chrome and get him to type in "www.google.com" "www.bing.com" etc. but it always says he is not connected to a network even though he just signed up for the TMobile plan and the tablet (Samsung Galaxy Tab 4 8") says he has 3 to 4 bars at all times. Now is the tablet misinterpreting cellular reception or did TMobile mess up and not activate the sim they put into the device.

 

[nahoku]

I'm guessing he's looking at the cell signal if he's describing 3 or 4 bars. You can't browse the web on the cell signal used for making phone calls. He needs to turn on his data connection, if he indeed signed up for a data plan, or use/turn on wifi.