Next Monday, Leicester Tigers legend and Rugby World Cup winner Kay is taking on the challenge with fellow BT Sport presenter Martin Bayfield to raise money for Sport Relief and the Royal Marines Charitable Trust Fund.
"I want to beat his time to the bottom, definitely,” said Kay. "Whenever you put a rugby player next to another rugby player there is an element of competition in everything.
"I don't know about his weight but it's about three steps for him.
“I wouldn't say I am totally scared of heights but I’m sure there will be a few butterflies.
"I quite enjoy the odd thrill-seeking activity. It is a real opportunity especially when we are raising money for such good causes.
"Abseiling down the BT Tower is something that people just don't get the opportunity to do so I want to enjoy it all the way down and take in the spectacular sights.”
After a training session with the Marines, Kay is looking forward to Monday.
"I have been very lucky over my career to have done a few bits of training with the Royal Marines and have always been massively impressed with them,” he said.
"I am really looking forward to it, much more now having done the training. The most nerve-wracking thing is when you first feel the harness hold your weight.”
Kay is hoping to raise as much as possible for the chosen charities as he and Bayfield struggle down the tower.
"The armed forces charities over the past decade or slightly longer have become so important to the UK,” added Kay.
"Guys who have found themselves in situations where they put their life on the line deserve to be supported.
"Sport Relief is becoming a real community thing. It is an opportunity for like-minded people to get together and raise money for worthwhile causes and get the benefit of being involved in sport. It is a fantastic charity.”
Bear Grylls, Helen Skelton, Mark Foster and BT chief executive Gavin Patterson will be joining the challenge, together with Premiership Rugby chairman Quentin Smith and directors Adrian Alli, Dominic Hayes and Wayne Morris.
To support Ben Kay as he abseils down the BT Tower – and help him raise more than Martin Bayfield – go to bt.com/bensabseil