busy signals

Please do not think me stupid, but my son tells me when you call someone, and the line is busy, but then try again and there is no asnwer, it means another person was trying to call them at the same time. Yes?

You can sometimes get busy signals from the telephone network, not the destination phone. Seems most likely, since most people have voice mail these days, and I haven’t heard a normal busy signal in years. When you get through, you find no one is actually there.

The simultaneus call is certainly a possibility.

You can get busy signals whenever the phone network is unable to connect the call.

The most common is when the callee is already on the line (and does not have call waiting). But the callee’s line could also be busy because another caller is ringing that line, like your son said.

But others could be:

  • the callee’s exchange (the 555 of 555-1212) has all incoming lines in use.
  • your exchange has all outgoing (inter-exchange) lines in use.
  • if calling to a different area code, the same applies: either the incoming circuits to that area code, or the outgoing lines from your area code are all busy.
  • if either party is on a cell phone, the same could happen at the cell tower: all the circuits from that tower to the rest of the phone network could be busy. (Though normally, there is another further tower (possibly not as good a signal) which can takeover and complete the call. But this does happen at disaster scenes, where too many people in the same vicinity are trying to use cell phones.)
  • if the call has to transfer between different phone companies, the same applies: incoming circuits at the other phone company, or outgoing circuits from your phone company may all be in use.
  • long distance lines may all be in use. This used to be common in coast-to-coast calls, when there were a very limited number of circuits between the US coasts.

There is a separate signal (‘fast busy’) that you will get in some of these cases. Or you may get a recording (‘all circuits are busy…’).

These used to be fairly common.
But now, the phone network has a much greater capacity – many more circuits than normal usage – so these are pretty uncommon. They mostly occur either locally near a disaster site, or regionally or nationally, when something happens that makes lots of people try to call others at the same time (9/11 events, Mothers Day, etc.).

It’s possible that no one is home, but an answering machine is handling an incoming call (if they have one). I don’t think this happens with voice mail, but I’m not sure.

A busy signal is sent to the caller whenever the recipient’s phone is “off-hook.” This doesn’t mean that they were trying to call YOU, just that their phone line was in use at the time.

Normally you have a busy signal indicating the line is in use, meaning it’s off the hook at the person you’re trying to call

If there is a problem with the line you get a “fast busy signal” which sounds like a normal busy signal but sped up

It could mean what the OP son said, or they could have been talking and hung up.

For example

Markxxx) I can’t talk some jerk is gonna call me for a date. I wanna get outta here fast, 'cause if I don’t answer the phone he’ll be at my door. Talk to you later

No, your son is right. Assuming simple, old-fashioned phone connection:

Sam calls Fred, and the phone rings and rings. the line is “engaged” by the connection. Bill calls Fred while Sam is listening to that pretty ringing. Bill will get a busy signal. I actually tested this as part of a VoIP conversion once upon a time.

Think about it. If not, what would you expect - Fred comes in the door, hears the phone ringing, and answers it. Fred and Sam talk. If any time from the beginning of the Sam-ringing, Bill calls, Fred will still pick up and talk to Sam. Bill can only get a busy signal.

In the good old days, and even today, if Bill gets a busy signal, it won’t change to a ring just because Fred hung up on Sam. Whatever happened when the connection was being established is the final result.

Of course, there are too many options - ignoring the business options such as ring groups (If phone A is busy, phone B will ring and so on - call centers)

If you have call waiting - many people can ring at the same time. I odn’t know what happens if you call while the phone is ringing, but IU bet you’ll hear the call-waiting sound as soon as you pick up. However, Caller ID is sent betwen the first and second rings (as RS232, IIRC) so you’ll miss the second caller ID info unless your phone can handle multiple signals.

Most likely nowadays, instead of busy you could go to voice mail if they don’t have call waiting. So the second caller will be directed to voice mail immediately because the line is engaged, rather than hear a busy signal…

RS232 is a physical connection specification, and it isn’t the one phones use. Caller ID uses the 1200 baud Bell 202 standard to send the information; if you think ‘modem tones’ you’re on the right track.