Yes, TELLIES is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, L 1, L 1, I 1, E 1, S 1.

Is it a valid word?

TELLIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an electronic device that receives television signals and displays them on a screen

Also: television receiver, television set, tv set, idiot box, boob tube, goggle box.

Not playable in Scrabble US: TV.