Giant images of BT's classic red K6 telephone box were projected onto several of the company's central London buildings, including its HQ near St Pauls, to mark the design icon's 80th anniversary on October 5th.
The K6, or 'Jubilee Kiosk', was designed by English architect Sir Giles Gilbert Scott (1880-1960) and first introduced in 1936 to commemorate the Silver Jubilee of King George V.
The kiosk became the first standard phone box across the UK.
Scott was also responsible for designing landmarks such as Battersea Power Station, Bankside Power Station (now home to Tate Modern), Liverpool's Anglican Cathedral, which also contains a K6, and Waterloo Bridge.
David Hay, Head of BT Heritage, said: "The red telephone box and in particular the classic K6 is an important part of the UK's history and regularly tops the polls as a design and cultural icon. They're recognised by people around the world. Many are now found in countries as diverse as the US, Cuba, Brazil, Switzerland, Hungary and Germany."
Out of a total number of 46,000 working public payphone kiosks on the streets of the UK, around 8,000 are traditional red phone boxes, of which the majority are K6s.
The architectural significance of the traditional phone box has seen 2,400 kiosks designated as grade II listed buildings.
BT is also providing for sale a limited number of refurbished examples of traditional phone boxes.
To commemorate the K6's 80th birthday a small number of kiosks are being painted in a Union Jack design instead of the standard bright red.
Since 2008 BT has encouraged communities where their local phone box is not being used to make calls to buy it with the payphone removed for £1 under the Adopt a Kiosk scheme.
More than 3,500 kiosks have been adopted and transformed into a variety of new uses. Some have been fitted with life-saving defibrillation machines, others have been turned into art galleries, mini libraries, exhibitions and information centres.
Neil Scoresby, Head of Payphones, BT, added: "The success of the Adopt a Kiosk scheme has shown the huge amount of affection communities throughout the UK have for red phone boxes, particularly the K6.
"They're loved around the world, so much so that lots of people have actually bought one from us. Owning your own phone box has been a huge hit and we think the Union Jack design will prove to be popular."