For one, you can take apart your TV and see that it doesn't have a SIM card
replyCan you spot a device like this : https://www.intersign.dk/cdn/shop/products/868e2a0dce897d05a...
reply
The linked image shows a module meant for easy integration, but it could also simply be a part of the main board of the TV. They could "hide" the GSM antenna alongside the wifi antenna.