August 1920                       The initial broadcast was "thought to have been heard by listeners in at least 30 Detroit homes". In 1921, 8MK would change its call letters to WBL and is now WWJ-AM, an all-news radio station. Pitney Bowles Mail Opener, Science Source.com Previously, postage meters had been used only by the post offices themselves. The Pitney Bowes company, which previously had provided meters to the post offices, was given exclusive recognition for use by businesses of the Model M, its simpler "mail marking machine and postage meter", which had been awarded a patent on July 18