In article , TELECOM Digest
> Editor noted in response to Robert Bonomi:
>> [TELECOM Digest Editor's Note: As Robert knows, those four additional
>> touch tone keys were known as A,B,C, and D. I forget the exact
>> meaning of each, but my question is, did anyone with 'regular'
>> service but with an Autovon phone ever try pressing those keys in
>> a regular call? I did a couple times, and the immediate result was
>> a 'fast busy' signal; the call would not complete. PAT]
> On the PSTN, it somewhat depended on the switch and programming.
> 'Reorder' was the very-common switch reaction. There were a few
> switches that completely 'ignored' those signals.
> [TELECOM Digest Editor's Note: But did you ever see/hear any that
> neither ignored nor offered re-order, but instead actually _did
> something_ ? I never did. PAT]
I knew of a couple of PBXs that used 'em for some call-routing selections. Twas an easy way to make a particular feature 'not available' from most phones, -without- having to get into extended "class of service" restrictions.
I never encountered a _telco_ C.O. that implemented any user-accessible functionality on them. I've got a vague recollection of some telco 'test' systems that used em _after_ the call to the test system was connected. Of course, that _wasn't_ the switch doing it.