he tower was closed to the public in 1971, with the restaurant shutting in 1980.
BT will hold a ballot for members of the public to eat at the restaurant while overlooking London's skyline.
Gavin Patterson, BT Group chief executive, said: "I'm delighted we're able to re-open the restaurant to the public.
"The BT Tower was a unique feat of engineering when it was first built and it remains an important and much-loved building today."