Ericsson Twin Box Phones
Fig 1: KTAS twin box phone, with Ericsson replacement parts. Note the typical small battery box on a narrow backboard. The original phone from which they were reconditioned was British Western Electrics model 5728/5730, built around 1900. It is also possible that the models with the switchhook mounted across the bottom of the top box may be an all-Ericsson unit. If the switchhook fork is shaped like spurs it will be Western Electric. The Ericsson unit used rounded ends to protect the Outside Terminal Receiver from damage.
Fig 2: New South Wales Railways twin box phone, with a wider battery box on a flared backboard. This seems to be the standard format used on the Australian and New Zealand phones. The bulk of the phone, including the switchhook, is a Western Electric Model 5731, again from around 1900.
Fig 3: An original Bell three box phone with Blake transmitter, and the Ericsson-reconditioned version with an LME transmitter replacing the Blake, and LME OST receiver. The Bell model appears to be an earlier version of the Western Electric Model 5722/5727. Most of these phones will have retained the Bell / Western Electric generator.
Fig 4: These turn up in the United States from time to time. They are ex-KTAS phones of the model shown in Fig 1, and were reconditioned for sale overseas after they were recovered from service. Thus this is the third incarnation of these phones - Bell, Reconditioned Ericsson, reconditioned again for overseas sale. The large transfer is typical of these models.
Fig 5: An early U.S. twin box phone. Similar phones have been identified from Illinois Electric and Plummers. Although this one has Ericsson on both boxes, this is likely to be a manufacturers advertising gimmick rather than a true picture of the phone. Plummers seems to have been building twin box phones with branded Ericsson parts through the 1890s.
Fig 6: Inside a typical Bell or Western Electric top box . Note the WE generator with red magnets, which was retained in most Ericsson conversions.