That is the GPO No. 746 phone exactly, bar the NZ-specific stampings on the base and the backward dial. Even the connection block is the same as the ones which were used here.
The 746 was introduced around 1967 as a revised version of the 706, the latter having become the standard GPO desk set in the late 1950s when it displaced the old 300-series phones like the one in the other thread.
The most obvious external difference between the 706 and 746 to the casual observer is the shape of the case around the handset area, although obviously there were quite a number of other changes.
706 and 746 refer to the basic desk phones; other numbers in the 700-series were used for wall phones, PBX phones with extra buttons, and so forth.
You can see a range of 700-type phones here:
http://www.telephonesuk.co.uk/phones_1960-80.htm Your phone has the later single-coil ringer, Does it have the bell adjuster on the front too?
The earlier 746 phones used the more common double-winding ringer,
like this one .
The "mystery" devices in the black package are actually a type of thermistor, used as part of the regulator circuit (and the green unit you queried is in fact a rectifier package).
As for lighting up, if you look closely at those thermistors in a darkened room with the phone off-hook, you will see that they do actually glow!
Here's the basic 746 schematic:
![[Linked Image from telephonesuk.co.uk]](http://www.telephonesuk.co.uk/images/8746_cct.jpg)
On the earlier 706 model, the whole regulator circuit was on a separate small plug-in circuit board. This board had contacts on both ends, those on one end just linked across so that the regulator could be bypassed by simply reversing the board in its socket.
Click here for 706 Schematic .
[This message has been edited by pauluk (edited 04-21-2005).]
