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Refugee · 26th May 2019, 1:18 pm

The DTMF chips have lead outs for 16 keys and not all are connected on domestic phones.
The guy reckoned that one of the extra keys could activate call back even if the calling number was witheld.

26th May 2019, 1:18 pm	#27
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: "Butt" 'phone The DTMF chips have lead outs for 16 keys and not all are connected on domestic phones. The guy reckoned that one of the extra keys could activate call back even if the calling number was witheld.