RonB, Paulo - phone tech question

Question

Hey, you two phone-techie-whiz types, I have a situation in my latest script wherein my hero, who is away from home on business, receives a phone call in his hotel room from his distraught wife back at home. During the course of the conversation, something awful happens that causes her to drop the phone, leaving it off the hook. I'm under the impression that there's no way for my hero to call her back on that phone, or for him to get an operator to ring it, or anything like that. Am I correct?

What I have him do is make a call via his cell phone to a relative who lives in his town and ask him to get over to his house to see what's happening. Just wondering if this is a realistic sequence of events.

Thanks.
Gene

Usenet · Accepted Answer

[nq:1]Hey, you two phone-techie-whiz types, I have a situation in my latest script wherein my hero, who is away from ... on that phone, or for him to get an operator to ring it, or anything like that. Am I correct?[/nq]
You'll have to ask my brother. I'm not a real phone man, I only play one on this newsgroup. I'm pretty sure you're right however. I think when you "break the loop" you can't send ringing voltage to the phone until it's back on hook. I think the best that can happen, is that an operator can cut into the call but he/she would just be yelling "Is anyone there" like the husband would.
I'll ask El Paulo.
(Now Kyle could probably have answered this question in a heartbeat but since he moved to Hawaii he's posted what... three times? Harumph!)

RonB
"There's a story there...somewhere"

Usenet · Answer

[nq:1]Hey, you two phone-techie-whiz types, I have a situation in my latest script wherein my hero, who is away from ... to get over to his house to see what's happening. Just wondering if this is a realistic sequence of events.[/nq]
If the wife dropped the phone and if he didn't hang up, then the call is still connected unless it landed on the hook-switch and hung up the phone. (Of course, normally people would think: "I got disconnected", they would hang up, lift the receiver, get dial tone, dial the number and get a busy signal.)
Technically, the ringer circuit is always connected to the Central Office, whether the phone is on-hook or off-hook. So technically it could be rung at any time. A phone is rung with AC voltage superimposed over DC voltage. (I don't know if that's the technical way of saying it, but that's what happens.)
But practically, that ain't gonna happen. When you lift the receiver (go off-hook) it completes the circuit to the Central Office. The switch sees a signal, acknowledges it and sends dial tone. When the first digit is dialed it pulls the dial tone back off.

When a phone is on-hook, there is no DC current going to the phone. The only connection is to the bell, which is waiting for AC current to ring. When the phone rings, and is picked up, the Central Office detects a signal and stops the ringing. It's going to be pretty hard for a operator (or a tech) to override that.
Also, because ringing and "dial tone" use just as much (or more) of the Central Office resources as a completed call and because it's not making the phone company any money they've built timers to limit the amount of time a non-paying function can be used.
If you dial a number and let it ring, they'll give you about three minutes (sometimes less) then cut the call off sometimes with a message, something like: "The called party is not answering, please try your call later", and then they disconnect the call.

If you go off-hook, get dial tone, and don't do anything, after awhile you'll go into "lock-out", usually Central Offices will send loud, obnoxious, ear-piercing, screechy noises to tell you to "hang up, stupid", before it puts your line into lock-out.
When your phone is in lock-out, it's incapacitated. The only way to get it back out of lock-out is to break the circuit by going on-hook. (You could also cut the wires, but that's a little drastic.) By the way a short across your phone wires looks like the same thing as an off-hook to the Central Office. It just completes the circuit before it gets to the phone not inside the phone. So it also causes your phone line to go into lock-out.
So a typical scenario for the wife and husband would be 1) Something happens and she drops the phone. 2) He thinks the line got disconnected and he hangs up and tries to call back gets a busy signal. 3) When he hangs up the connection is broken to the wife's phone. 4) Eventually the wife's Central Office realizes A) Her call is no longer connected and B) She's off-hook let's give her dial tone. 5) The Central Office eventually gets *** sends obnoxious noises and puts her phone into lock-out.
What was the question again?
Oh, yeah. Your scenario works. Or you could have the wife drop the phone on a tile floor and have it break.

Paulo Joe Jingy
Sometimes some things just ain't right.

Usenet · Answer

[nq:1]So a typical scenario for the wife and husband would be 1) Something happens and she drops the phone. 2) ... Central Office eventually gets *** sends obnoxious noises and puts her phone into lock-out. What was the question again?[/nq]
I don't think that was Gene's question.
You know how when someone calls you, and you hang up but they don't, if you pick up the phone again it's still them at the other end? The connection isn't broken until the calling party hangs up.
jaybee

Usenet · Answer

[nq:2]Hey, you two phone-techie-whiz types, I have a situation in ... to ring it, or anything like that. Am I correct?[/nq]
[nq:1]You'll have to ask my brother. I'm not a real phone man, I only play one on this newsgroup. I'm ... have answered this question in a heartbeat but since he moved to Hawaii he's posted what... three times? Harumph!)[/nq]
There is a loud 'waugh waugh' sound an operator can send to a phone. If you leave a phone off the hook long enough it may get triggered. It's pretty loud, enough that it wouldn't be ignored in any reasonable sized house.
-sam

Usenet · Answer

[nq:2]So a typical scenario for the wife and husband would ... puts her phone into lock-out. What was the question again?[/nq]
[nq:1]I don't think that was Gene's question.[/nq]
It wouldn't be the first time I didn't answer the question.
[nq:1]You know how when someone calls you, and you hang up but they don't, if you pick up the phone again it's still them at the other end? The connection isn't broken until the calling party hangs up.[/nq]
For around ten seconds. (At least in the United States.) If you hang up for about ten seconds it will clear that call. Otherwise some vindictive idiot could disable your phone, simply by not hanging up.

The Nortel PBX (and probably their Central Office switch) has a rarely used feature called "Called Party Control". (AT&T and other Central Office switch makers possibly call it something else.) If you have this feature you can hold the call indefinitely (In fact, if you don't hang up you can even unplug the phone, then plug it in a week later and that call will still be connected.) We experimented with it on the Marine base at 29 Palms, because this feature used with "Malicious Call Trace" was freezing the switch up. It ended up getting fixed with a software patch.

Paulo Joe Jingy
Sometimes some things just ain't right.

Usenet · Answer

Thanks, guys. I knew this group was worth sump'm.

Gene

RonB, Paulo - phone tech question

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