User-added buttons on 300 series 'phones?
 

Hi all,

I have a GPO 300 series (or similar) which has a metal push button installed low on the front (below the dial, and above where the drawer would be).

To me it appears that the button may have been added retrospectively by a user by drilling a hole in the case - it doesn't match the kind of buttons I'm used to seeing on 'phones with 'Call Exchange' or 'Recall' buttons fitted from new.

Is anyone aware whether adding a button such as this was a common practice, or what purpose it may have served? Could it have been a way to add a 'Call Exchange' or 'Recall' function to a 'phone which otherwise didn't have it?

Cheers,

Liam

Re: User-added buttons on 300 series 'phones?
 

Could you add a few photos:
- Top of phone showing area between cradle (just to see if AEP, ITI etc)
- photo showing the button from front
- photo of inside showing the button internal connections

Re: User-added buttons on 300 series 'phones?
 

Definitely DIY I’d say.

These phones, especially the non GPO equivalents, were often sold off for next to nothing to experimenters like us in the 1970s, so many will have been modified to some extent, often to form an internal intercom system.

My old school’s science department had a dozen with the dial replaced by a rotary switch, with external DC bells and batteries to form a very effective means of communication between all the masters’ labs.