GPO UNIT TRANSFER INTERCOM, 1935

This unit is fitted with two 'doll's eye' indicators, one (labelled Exch) for exchange line calling and clearing and one, (labelled EXTN) for non-multiple station calling and clearing.
The unit contains a buzzer which can be operated by both indicators.

Your comments:

• I used to install these in late 1960's early 70's as part of BPO type inter phone systems for the NZPO. They were limited to 2 exchange lines which could be transferred to any of 12 extensions.
  The 'dolls eye' indicators were simply called 'eyeball indicators'in NZ.
  .......... Arthur Williams Awarua Radio Communications Museum, Invercargill New Zealand, 30th of September 2012
  
  

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