Shocked jocks' O2 calls crossed with Brummies, now everyone's cross O2 customers in Birmingham have been listening in to callers in Scotland with the kind of crossed lines not usually experienced on a telephone network for decades. The problem isn't widespread, but O2 has confirmed that customers around Birmingham have found themselves lurking on Scottish calls in an unrequested party line, …
Crossed lines get their name from the first automatic phone networks, based around a "crossbar" switch
Nonsense, crossed lines predate crossbar switches by at least 20 years, and probably longer.
There were a number of reasons why you would be able to overhear another call. In the early days of paper and lead insulated cables, (still in use in the 70s and 80s) you could end up with cross-talk between pairs if the cable got wet.
For actual interconnection of calls, these could be caused by the operator plugging a call into the wrong jack, and later, on Strowger exchanges, they could be caused by the wiper stepping to the wrong contact due to relay stutter.
To some (and often unfairly) Corby, the former steelworks town closed in Maggie Thatcher's time, is an outpost of Scotland.
With 10,000 plus Scots having moved there for the Steelworks, the town grew and grew.
If you have a scottish accent and are anywhere in Northamptonshire, it is assumed that you reside in Corby.
The Department of Work and Pensions were recently criticised for allowing the JobCentrePlus website to carry job adverts, for employment vacancies in Corby, with a LOCATION AREA of SCOTLAND.
I am sorry but crossed lines well pre-date the use of cross bar and other 'modern developments'. They could be caused by dropped solder on jumper frames, un-recovered wiring on jumper frames and other inter tag bridging on the frames. Then there were the mechanical issues, broken 'P' wires on switches, faulty wipers bridging, crossed joints in cabinets or joint chambers and so on, then there were the issues of water ingress and a few times deliberate actions, think illegal home made wire taps. This 'wonderful' variety made it so 'interesting' to fault find.
Modern switches such as cross bar and some, (probably more than 'some') digital switches introduced their own twists on the crossed, i.e. unwanted multiple connections. All of these could be either one way 'taps' or both-way 'taps' allowing both parties to be heard. Some times the 'added value' could be free of charge and sometimes not...
Of course some of these caused service loss, so you might only be able to listen into other people's calls when you would probably have more incentive to complain. In other cases you might never get the same callers twice.
I remember joining in with early mobile phone calls on a 934Mhz CB that belonged to the dad of a friend who fixed radios for a living. The 934 band had 20 channels, but the expectation was that this would be extended later and so could be done easily with a switch on the circuit board.
..and Mrs YAC.
Only we ended up being unable to hear each other, and the other call could not hear us either. Rather oddly I could hear one side of the other call, and my wife the other call's counterpart. Together we could piece it together. Or at least the 30 seconds I heard while I was yelling "HELLO!" rather loudly. Other people's conversations are actually quite dull.
I am surprised the paper hacking chaps don't leap on this and say "it was a crossed line! I just happened to have a crossed line with <Z list celeb> and <other z list celeb>. Five times. And their voicemail. Twice.
Happened to me last week too, on a call to my wife, which while the call was in the ringing stage and waiting for my wife to answer. Could only hear one side of another call, which was short, and then dropped out back to ringing. Couldn't perceive any obvious accent on the girl I could hear (who apparently was still in bed and wanting a cup of tea.) Both me and my wife are on Orange/EE.
We had a party line when I were a lad. You could both receive calls, but only one could call out. So if you picked up the phone to make a call, and they were yakking away, you couldn't call out. Although you could always interrupt them, until they went away.
I think the theory was that you weren't supposed to know who you were sharing with, which supposedly would make eavesdropping less fun. But we found out when their kitchen caught fire. My Mum phoned the Fire Brigade, as she could see it as the gardens backed onto each other. But the other woman was also phoning the fire in. So Mum said, "you leave the house and get to safety. I'll call the Fire Brigade for you."
And she said, "No. It's my fire. I'll call the Fire Brigade!" After a bit of to-ing and fro-ing Mum realised that she was a bit too flustered to act rationally, so gave in and put the phone down, before the house burned down...
I've remember getting a crossed line when I first had a mobile phone. I could hear their conversation, but they made no sign of being able to hear me. However it was barely audible. They sounded more like Charlie Brown's teacher.
But, yeah, "I ain't Spartacus" we had the same when I was a kid, about 50 years ago. I seem to remember having to press a button on the top of the phone for some reason to make a call...Often picked up to hear the other party talking.
(Party line, for those too young to remember was a shared line with another dwelling, usually nearby. BT (Post Office or GPO then) didn't have much capacity. Crossbar wasn't the first, it was the "Monkey-on-a-stick" Strowger exchanges. As an apprentice with the GPO, I had to learn about those (and do the weekly cleaning of a thousand or so switches). Slugged relays (Ring of iron around one end of the relay coil) - top-slugged for delay to open, bottom-slugged to delay closing. Now, that was art, not science!)
At last a man who knows his history. Yep, Strowgers were the first and a lot of them outlived Crossbar exchanges. The latter were pushed by a Labour politician of the 60s and 70s - dear old The Right Honourable Anthony Wedgewood Benn (a.k.a. "Tony Benn") when he was Minister for Technology(?).
Phil.
"But, yeah, "I ain't Spartacus" we had the same when I was a kid, about 50 years ago. I seem to remember having to press a button on the top of the phone for some reason to make a call...Often picked up to hear the other party talking."
If memory serves me correctly, what you had there was specifically an "R-party" line - two subscribers per line, each of whom obtained dial tone by pressing the button, which placed an earth on one leg of the line to obtain dial tone. The call was then held by the loop in the normal manner.
By ensuring each party drew dial tone by earthing a different leg of the line it was possible for the exchange equipment to determine which of the two subscribers had initiated the call, ie., each party on the line had their own line circuit relays in the exchange - this allowed automatic metering for the call to take place.
I think (conventional) ringing was applied one leg to earth, so you only heard ringing for calls directed to you.
The other party line type was the "M-party" line - 5 or 10 subscribers per line, dial tone pulled by a loop on the line, a single line circuit so no identification of who the call was initiated by, coded rings (morse coded letters) and every subscriber received every ring.
It's been a while (40 years last December) and those days seem a long time ago - but yesterday a 40 year service award fronted up on my desk, so I guess I'm luckier than most of the people I started with back in '72.
Speaking of party lines, anyone else remember 1 & 1 carrier (or WB900). I fitted a few of them over the years.
One subscriber had a normal analogue pair, and the other subscriber used the same pair but their audio signal was carried by modulating a 40Khz carrier signal down the same line.
Filters at the subscriber premises and exchange kept the two signals apart.
I remember we used to have problems with the carrier subscriber picking up radio signals from the BBC.
Funnily enough, this only seems to be affecting my Asian friends and colleagues, and they've all said that they've ended up hearing a quite upset lady speaking Hindi. I was blaming their iPhone 5's (because that's what they all own) but now it appears to be more indepth than that.
Had this calling an o2 from Virgin. Friday about 4.30pm in Birmingham. Got to hear 3 calls one after the other over the space of five mins or so. I was going to write to you Reg to tell you but forgot, and didn't expect it to lead to much anyway,
But it shows that even mobile-mobile calls are not secure... Or at least not as secure as one might expect.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
