GPO Nomenclature re: CB to Auto

[russell_w_b]

Would the GPO have marked subscribers' telephones with an extra stamp or label indicating that a dial had been retro-fitted to a (typically) 300 series C.B. instrument upon either:

Exchange upgrade from manual to auto, or -

Swapping out the instrument from a C.B. to an Auto exchange?

Considering the first example, would subscribers whose exchange have been upgraded from manual (C.B.) to auto simply be provided with a new instrument?

Or is it considered acceptable that an instrument fitted with a dial can be stamped (say) 332 CB? (or, conversely, but no doubt unusually) an instrument stamped (say) 332 L can have a blanking plate?

In other words, was there an identification and records procedure to be used when telephones were converted, for whatever reason, from one type to another?

[Station X]

I don't know about 300 types, but in my experience 700 types were never converted. They were simply changed.

[russell_w_b]

Originally Posted by Station X

'but in my experience 700 types were never converted'

Interesting... I have a 710 (ex-Exeter MF BBC transmitter site) that is marked as 710 CB. It is fitted with a dial, and was in use as a dial telephone when I acquired it!

[davidw]

IIRC you are both right! When I was on the changeover team for Kesgrave Exchange in 1968 (just down the road from Graham..manual to crossbar conversion) we changed the phones for customers on site. The old CB ones went back for refurbisment and came out cleaned ,fitted with a dial and with a sticky label marked L.

[russell_w_b]

Originally Posted by davidw

'The old CB ones went back for refurbisment and came out cleaned ,fitted with a dial and with a sticky label marked L.'

Thanks. Would this re-furb extend to altering any labelling inside the telephone (chassis stamp, paster diagram), or would it be restricted to the base?

[davidw]

IIRC the inside diagram had a sticky over it, but don't recall any other marks.