zweig@cs.uiuc.edu (Johnny Zweig) (11/26/90)
I was just listening to the seventeenth message in a row on my answering machine that says "If you would like to make a call, please hang up and try it again" and got to thinking: for POTS, what indicator is there that the party on the other end of a connection has hung up? Is it just the dialtone(*), or is there some other kind of signal (line-voltage, say) that lets you know? I understand that ISDN will have hang-up messages on the D-channel, so maybe I should just rush out and buy one of the ISDN answering machines I've been seeing all those ads for. Johnny Curious (*) followed by silence followed by the stupid announcement followed by that loud beeping followed by more silence
tad@ssc.UUCP (Tad Cook) (11/29/90)
In article <14947@accuvax.nwu.edu>, zweig@cs.uiuc.edu (Johnny Zweig) writes: > I was just listening to the seventeenth message in a row on my > answering machine that says "If you would like to make a call, please > hang up and try it again" and got to thinking: for POTS, what > indicator is there that the party on the other end of a connection has > hung up? Is it just the dialtone(*), or is there some other kind of > signal (line-voltage, say) that lets you know? In most modern electronic offices there is a signal called the CPC Pulse (I don't know what CPC stands for ... Calling Party Control maybe??) that happens when the other party goes on hook. It is a brief interruption in battery on the line. Many answering machines can respond to this, so that they will reset and stop recording when the other party hangs up. My Panasonic machine even has a CPC switch on the bottom for disabling this feature. Unfortunately, there is no signal to tell you when the called party has gone off hook ... which is why COCOTs have problems deciding when to collect your coin. Tad Cook Seattle, WA Packet: KT7H @ N7HFZ.WA.USA.NA Phone: 206/527-4089 MCI Mail: 3288544 Telex: 6503288544 MCI UW USENET:...uw-beaver!sumax!amc-gw!ssc!tad or, tad@ssc.UUCP