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Landline Fix

Thinking about a project? This is the place to share your ideas and gather information.
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JDISME
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Landline Fix

Postby JDISME » Sat Jul 11, 2015 4:20 am

Hey all,

So, I have a situation where I have a landline again and I have been interrupted. Some may say, "thats why I got rid of it", but oddly it is a lot more useful than a couple calls when I'm sleeping. ;)

Project Idea:
Create a device that is between the source phone signal (incoming twisted pair) and phone. If I control the connection of the twisted pair, I can either connect them to allows a call to go through and ring or disconnects and sending my caller to Voice Mail. What that would do is allow me to do, is set a Do Not Disturb function controlled by a time set that I have programmed, rather than trying to punching some codes into my phone every time I go to sleep and wake up (which I will admit, do not remember to do). I don't know how many of you out there has been woken up by the needless noise of someone trying to get a hold of you when it is not an emergency; I believe we have micrcontrollers to help with these inconveniences; without the need of always remembering to set the phone before a long night programming or gaming.

My Ideas:
I was thinking of a prop at the helm of course, but perhaps a BS2 just cause the forums need something on the topic. Also some relays controlled by transistors to handle any signal coming in. I have not metered or O-scoped the signals, so I do not know what voltage levels I should expect; however I can't imagine it's too much higher than a couple volts.

Questions
Anyone work with phone lines and what are their voltages? Does anyone know what the signal is coming in? For example, the signal from my provider gives date, time and all that as well, if I know how it talks to the phones, then perhaps I can use that time format to control when phone settings.


Thanks,

JD
Joshua Donelson

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Granz
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Re: Landline Fix

Postby Granz » Sat Jul 11, 2015 8:54 am

Ignore the voltage levels, the ring signal can get up to 90V (by spec, some can get higher.

You can use a ganged DPST relay:
Image
T=Tip, R=Ring. Tip and Ring on right side of picture are from the telco (telephone company,) and the signals on the left side go to the telephone and the answering machine. When your relay is not energized, the call goes through to the telephone. When you want privacy, the relay is energized (high on the I/O pin, and ground on the other side of the coil) and the call goes through to the answering machine. You just need to set the machine to no ring, or silent mode. If you still need to be able to monitor incoming calls, add an extra phone (with ringer turned off) to the answering machine.

Just hook up the Prop I/O pin to your Prop (or any other controller, or just a switch [follow normal I/O rules, like using a flyback diode.]) This way, you do not need to worry about voltage levels, signalling, etc. Let the telephone gear worry about that.
Art G. Granzeier III, President
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Re: Landline Fix

Postby JDISME » Sun Jul 12, 2015 4:32 pm

Thanks for the good idea, looks easy and functional; however I would like to de-code the signal coming in from the line. For example, setting the time and date of a new phone when it's plugging it in. Also I do not have a answering machine with this phone setup, it's Voice Mail for any messages. So if the phone doesn't pick up, or is not connected, it goes directly to Voice Mail.

90+ V !!! thats a lot higher than I was expecting, but I can't imagine there is a lot of current. That will be interesting to see on the scope or/and meter. Do you know how the telco sends data or in what format?
Joshua Donelson

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Re: Landline Fix

Postby Savage///Circuits » Wed Jul 15, 2015 4:23 pm

If I might offer a simpler suggestion. Most modern Panasonic phone systems offer a timed silent mode. I use it myself at home. The phone next to my bed stops ringing between 11P and 6A and the one in my office doesn't ring between 8A-5P so I don't get interrupted while on a work call from my business phone.

While I am all for building something with a microcontroller, I find this solution better because the phone also has an answering machine, 250 number call blocking and newer ones can even locate your cell phone for you. :ugeek:
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Re: Landline Fix

Postby JDISME » Fri Jul 17, 2015 2:07 am

Really?? Nice... that is fantastic. However, that tells me is that I can in fact, make something easy that should be able to do with a Prop. :) I think there has to be a easier way (other than upgrading my phone), and build it up. Should make for a cool project once it's done. Thanks for the info, that helps me out.

I have read some about how telephones work with DC signals for on hook or off hook, and AC voltage signals for the phone call. Then I remembered I used VoIP and it works differently. lol :lol: Soooo I had to read more about the signal levels of VoIP and what not. After all that, I'm going to get some wire snips and scope the lines coming off the wall and and see what happens.

I have a couple phone cables coming to me via Ebay, and I have the scope ready to run some tests. If I dont get them in the mail by Friday, I will probably just go to The Shack.. haha or Walmart at that point, and pick something up for this weekend for testing.
Joshua Donelson

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Re: Landline Fix

Postby JDISME » Sat Jul 18, 2015 6:04 pm

Using the twisted pair wiring below, I scoped the lines and didn't get anything more than noise it looks like. I will have to read up and see if I can figure it out. Then just see if I can use some transistors to connect or disconnect them as a given time. :)

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(136.24 KiB) Not downloaded yet
Joshua Donelson

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Re: Landline Fix

Postby MrBi11 » Sun Aug 09, 2015 1:02 am

You could also add more features like:

When the machine answers and the caller enters the proper DTMF sequence (i.e. dials the right number) it could generate a ring voltage to your phone and detect when you pick it up and switch the Co line to the phone from the answering machine. People who know the 'code' could still call you in the event of an emergency, etc.

also, since you're already detecting off hook from any of your phones you could have it switch the line back on when a handset is picked up to make out going calls automatically and switch back to DND mode when call is finished.

Note: anything connected to the phone line needs to be approved by the FCC I believe.

to detect DTMF with a propeller:
http://obex.parallax.com/object/746

to generate a 20Hz sine wave for ringer:
http://obex.parallax.com/object/378
(note: you'd need to pump it up to 90V)

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Re: Landline Fix

Postby JDISME » Sun Aug 09, 2015 7:27 pm

Mr. Bi11,

Thanks for the tips and prop code, I am still working on the whole project. I am using VoIP services, and looking at the lines on the o-scope; it doesn't seem to follow the same voltage pattern as the 90V I expected; but rather much lower and looks like static. I got some rj11 cords from ebay china, but I must have read to quickly and they are not correct; the signal doesn't pass through. I have been waiting on the parts I ordered, so I will just head to the Stack and pick some up and get back to it.
Joshua Donelson

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Re: Landline Fix - Do not need anymore

Postby JDISME » Wed Sep 30, 2015 5:22 pm

Hey All,.

Well I ended up getting rid of the phone line, starting to cost too much for not using it enough.... on to the next project. Thanks for all the tips, but I just unplugged the phone as the solution while I had it.
Joshua Donelson


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