atcomsystems.ca/forum Forums General General Telephone & Systems Information Disconnect Supervision Problems

Lately, when I've been making multiple phone calls back to back, and when I disconnect, and try to make another call, the previous call is still in progress. I know I'm holding down the switchook long enough to disconnect instead of activating flash. I've had this issue before, and it is very irritating because half the time I have to hang up to get a new dial tone instead of waiting and making another call because D.S. is so lousy these days. So usually I have to wait around 2 to 5 minutes before I can make another call. For example this evening, I was checking my voicemail, and forgot I can't enter my password on a 500 set (ha ha) and so I hung up and went into the other room to use the TT phone in there, but the line was still connected. I picked up the phone in time to hear the voicemail say "Thank you!" and disconnect. I tried flashing the switchook, and it did nothing. I picked up again to hear the typical two pop sounds you hear when the other party disconnects, and about 6 seconds of silence followed before I heard two rings and then "If you'd like to make a call.." about twice, so I hung up again, waited thirty seconds and picked up again to hear the ear piercing "off-hook" tones. I hung up and this time waited about 3 minutes, and this time I got a new dial tone. Does anyone know why this happens, and is it an error with the line status scanner at my CO? Any information would be appreciated, thanks!

Have you tested your line for metallic faults?

Or for (foreign) high capacitance?

What ringer equivalence do you have installed on the line?

Have you disconnected all except one phone and made a few test calls?

Or all phones, and made a test call from the NID?

Have you had the LEC do a test of your line?

I'm afraid most of those questions are a little to sophisicated for me, as I'm still a newbie to the world of phones. However I can tell you that I have two 500 sets and an AT&T cordless system with one cordless extension plugged into my home line, and I've only had this problem maybe 3 or 4 times ever but I don't like the idea of having a tied up phone line that I might need for an emergency. I will try making a call from the Network interface when this happens again, which I am unfortunately unable to predict when that will be.

By "ringer equivalence installed," are you talking about incoming ringing voltage or the ringing equivalence of the telephone set? It's getting late so I will have to get back to you tomorrow on this, an sorry for the lack of detail. Thanks for your quick reply!

If you have a toner with a continuity check on it, or a volt ohm meter just look for disconnect supervision at the demarc. Put the voltmeter or toner on the line, place a call, hang up. Very quickly the voltmeter should drop to zero than return to around 48 volts. The lamp on the toner should go out than back on. If this doesn't happen the CO is not returning disconnect supervision. Now this is on plain old pots lines. If you are using some type of IP based lines (cable) they probably don't even know what line supervision is.

Oops- I just re-read my post and I realize it sounds like this happens every time I try to place a call. This actually happens quite rarely but is very irritating when it does... Is this just a minor glitch with the telco's line status scanner? I know there isn't anything wrong with my wiring because this happens very rarely. Thanks for the responses!

Intermittent problems are tough to troubleshoot so don't rule out your wiring just yet. I've found where a spider crawled inside an unused modular jack and was fried by ringing voltage that caused the exact same problem you are experiencing.
That said, I would problably suspect a bad telephone set. The next time you have this happen, unplug your phone sets one at a time to see if this will release the line.

I think that telecom guy10 got it backwards.

Disconnect supervision is SENT by the phone company TO YOU that the FAR END has hung up.

The problem is that YOU are not sending a correct disconnect TO the phone company.

It sounds like BobRobert and ttech are right on the money: the problem isn't CPC related, but rather that your phone is not really hanging up, either due to a bad phone or a jack/wiring issue. A high resistance short in a jack (such as the cooked bug) might not conduct well enough to take the line off-hook, but may conduct well enough to keep it off hook after you hang up your phone. Temperature and humidity can affect the cooked bug (for example), hence the intermittent nature of the problem. Another clue to this would be a loss of volume - how is the audio quality on the line when this is happening?

Jim
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Calling Text Messaging a new technology is like saying that the folks who make Bic lighters discovered fire.

Might also be a failing capacitor in one of the two 500 sets' ringer circuits. Disconnect the red wire coming from the ringer coil from terminal R on the network inside the phone. Put a piece of tape over the end of that wire for now and test the situation for a few days. If this works, you've isolated the cause and this is a fairly easy fix.

Thanks for all the information, but I don't think there is anything wrong with the 500 sets- I've never had this problem before with these same phones at my previous house. The house was built around 2001, so the jacks are all in good shape. Ed, thanks for the wiring suggestion, and I will try that next time this happens. This problem is intermittent and hasn't happened for several days. This happened twice with my brand new AT&T cordless phone twice before it ever happened with any of my many R/D and TT old style desk phones. I will check my phone jacks just to be sure no previously-living creature met it's demise from everybody's friend ringing voltage! Thanks for all the suggestions everyone! Also Ed, since you seem to be quite knowledgeable about phone wiring (what an understatement) judging by some of your posts around the forum, I have an older Stromberg-Carlson R/D wall phone that does not ring- it's probably the capacitor, the phone is about 32 years old... But anyway I will pull it out of my telecom vault (a.k.a my bedroom closet) and take a look at it at some point this weekend. Thanks again everyone!

Another question of mine just popped into my head- why is there a pound (#) button on a TT phone anyway? If I press it I just get a reorder signal. I know it's used for telco speed dial features on cellular phones, for example, WKRG (news) vans here have small decals that read:

If you see news happening,

DIAL #555

CellularSouth

I know this feature is obviously only accessible to Cell South customers, but why doesn't it work on landlines?

The WKRG people are just assuming that you are in your car behind them and will be using your cell phone to dial that code.

* and # were developed on land line phones to enable callers to have the equivalent of "flexible 11 and 12 keys". Only the machine you called only knew what to do with these keys. Regular phone calls didn't need them.

This was an example of the 1960s getting in touch with tomorrow. Bell Labs saw the phone as being something more than just a device for talking. These keys were (are) used widely when communicating with voice mail, banking services, complaining about your phone bill, etc. today.

Because cell phones require the "send" key to complete a call, the * and # can be included in the number as wild cards. This also means that there isn't the need for the mandatory 7/10-digit format for the called number. What you are seeing are essentially speed dial codes.

These codes on cell service provers are just marketing tools. They are sold by the cell service providers to TV or radio stations. They are making themselves easier to reach than expecting a caller to jot down a phone number while driving. A few simple digits will result in an immediate call, whereas if you have to actually write down/remember a full number, you might not. They pay for the call, similar to dialing someone collect.

These stations are getting a bunch of money in return for this investment. If they are the first to report anything on the news, they get bragging rights when it comes ratings and award time. That is a coveted accomplishment in their industry.

telecom guy10, hats off to you for taking the time to read older posts! A confession: At least half of what I know about telecom was learned by reading Ed's (and others) posts. There is a vast wealth of knowledge on this forum - the membership is about to reach 30,000 any day now. Thats a big WOW when you consider that the majority of members are real telecom professionals in the US and Canada. I think every state and province is represented here.

Now, on the topic of your particular issue: You mentioned that you doubt there is anything wrong with the 500 sets because you didn't have this problem at your old house. Actually, that doesn't really tell you much, because 1.) The capacitors have aged since then, and aging is what usually causes the problem Ed is talking about; 2.) The loop current and/or off-hook voltage could be higher at your new place (are these POTS lines?); and 3.) A spike could have "punched through" the dielectric in one of the caps recently, making it (electrically) leaky. This last one is unlikely, but possible.

The other thing to remember about the problem Ed is describing is that you don't need to actually be using the phone with the bad capacitor for this to happen. The ringer and capacitor are bridged across the line all the time, so if this happens when using your new cordless phone that still doesn't rule out one of the caps in the 500 sets as the culprit.

Good luck to you in your endeavors!

Jim
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Signature lines are currently on back-order. We apologize for any inconvenience this may cause.

Early DTMF (TT) phones only had 10 buttons on them. Each tone signal is actually a combination of TWO tones, one vertical and one horizontal. To explain:

The first horizontal row of keys (1,2,3) has the frequency of 697 hz. The second horizontal row (4,5,6) has the frequency of 770 hz. For 7,8,9 the freq is 852. For *,0,# the freq is 941.

The first vertical row (1,4,7,*) is 1209, 2,5,8,0 is 1336 and 3,6,9,# is 1477.

When you push the digit "1" you send a combination if 697 hz and 1209 hz. This use of the combination of two tones was done to prevent accidental dialing while talking. Because the tones exist in the realm of human speech it is possible for the human voice to recreate them, combining two distinct tones minimizes this effect (though it is still possible and still happens more often then you would think).

When Western Electric produced the first 10 digit tone dial they realized that they had created, as Ed said, a "free" 11th and 12th key. The tones were already there for them, it was just a question of putting the buttons in place.

The keys were not used much originally. I remember a Johnny Carson monologue on the Tonight Show where he compared the * and # buttons to a man's nipples - nice to play with but completely useless.

Early on PBX manufacturers used them for features (dial * for Call Pickup and # for Call forwarding) or used them as Central Offices do now, as primary digits for features (*69, *72 etc.) In a large plant it was very handy to have an extra set of digits - You already lost 0 for the Operator and 9 for Outside Lines. 8 was often taken up by Paging or LD Trunk access and your extensions often took up some or all of the other available digits. Having * and # available for features was very handy.

Sam

Wow you guys know your stuff! Well when I get a chance I will post about my non-ringing Stromberg-Carlson wall phone... I'm thinking it's something with the capacitor. Anyway thanks everyone!

And to add to Sam's post:
DTMF stands for Dual Tone Multi-Frequency

and now you know.

Don't forget about tha A,B,C&D keys

You mean FO, F, I and P?

And the Autovon keys!

https://en.wikipedia.org/wiki/Dual-tone_multi-frequency

Read and learn your ABCD's

[The keys were not used much originally. I remember a Johnny Carson monologue on the Tonight Show where he compared the * and # buttons to a man's nipples - nice to play with but completely useless.]
:rofl:

Here's another topic I've been wanting to bring up:

Is there really such a thing as digital telephone service?

Companies like Cox and Time Warner Cable boast about fiber-optic networks, but is it really any different than regular landline service?

Let's say I have Cox Digital Telephone service, and that I live in Virginia. I want to call one of my relatives long distance who lives in South Carolina, and whose landline provider is AT&T. At some point, I am assuming, as my call is routed through the different switches, I am crossing regular copper phone lines. But if, for example, I want to call my neighbor to invite him over for burgers on the grill, and he also has Cox Digital Telephone, I am assuming the call would have the "superior voice quality" because it is using Cox's fiber-optic network. Am I right?

Also, doesn't the age and type of telephone set used on the line to make calls affect the voice quality as well? A crackly 500 set I would assume would not sound as good as brand new vTech cordless phones..

This topic has already drifted all over. I think your question would be a good fit for a new topic in "Telephone Service".