3 ms·
Even the ringtone on POTS is 90VAC - used to excite the coils for the big ring bells you see on the top of old phones. Phone technology is pretty crazy in gene
by bri3d 12y ago
Even the ringtone on POTS is 90VAC - used to excite the coils for the big ring bells you see on the top of old phones.
Phone technology is pretty crazy in general - the ringing, dial, and busy tones used to be generated by a magneto attached to a crank and later by racks of DC motors attached to generator sets in phone company offices.
I think some ancient phone systems even used the AC frequency of the ring tone to ring different phones on a shared party / conference line.
- DanBC 12y agohttp://en.m.wikipedia.org/wiki/Party_line_%28telephony%29 http://en.m.wikipedia.org/wiki/Party_line_%28telephony%29 > Later, independent systems applied multiple ringing frequencies for fully selective ringing. (The Bell System eschewed frequency selective ringing.) The ringers in party-line phones were tuned to distinguish several different ringing signals so that only the desired party's phone would actually ring. In this arrangement the only inconvenience of a party line was occasionally finding the line in use (by hearing talking) when one picked up the phone to make a call. If one of the parties used the phone heavily, then the inconvenience for the others was more than occasional, as depicted in the 1959 comedy film Pillow Talk. I was going to say "not that ancient!" because I remember using a shared party line but that was in the 1980s, so pretty old I guess.