U's sign ex-Spurs keeper
The 22-year-old, who spent six years at White Hart Lane, has been looking for a new club since Spurs released him at the end of last season.
Kelly had been playing for non-league side Welling and had a trial with Cambridge's Third Division rivals Leyton Orient back in September.
Mansfield Town, Rushden & Diamonds, Colchester United and Southend United have all had a look at the custodian in the past, but Kelly will hope to impress the U's new coaching team of Claude Le Roy and Herve Renard at The Abbey Stadium.
Meanwhile, former Cambridge defender Matt Joseph has had a deadline day move back to The Abbey Stadium fall through after he picked up a groin injury in training.
He has since returned to his current club Leyton Orient.
