Why can't I use my computer as a telephone using POTS?

[RandFan]

Ok, I'm NOT talking SKYPE (http://www.skype.com/) or anyother VOIP (http://en.wikipedia.org/wiki/Voice_over_IP). I'm talking a computer, 56K modem, headseat and POTS (http://en.wikipedia.org/wiki/Plain_old_telephone_service).

That's it. I'm damn certain there was a time that I used to be able to but that might be a false memory.

I can use my computer and modem to dial but to talk I have to pick up the handset and talk through the handset. Why can't I talk through the computer using the headset like I could with VOIP?

It's bizarre. There's no technical reason. There is nothing special that a phone does that a modem and computer couldn't.

I've searched and there is just no information on the web.

I'm sensing a bit of déjà vu so if I've asked this question before then please forgive me.

[NewtonTrino]

So attach your PC to the phone line using an appropriate connection? You would need a D/A converter of some sort so that the line voltages etc. are correct for the phone system. If you had that small bit of hardware then sure, you could use your PC as a phone. But why? You would still need to subscribe to regular phone service and skype is super cheap and has video!

[grmcdorman]

The computer modem needs extra features (meaning hardware and cost) to support voice. They do exist, though; I have an old - and unfortunately broken - one at home. Most modern computer modems only support data and fax.

Search for "voice modem" for more details; e.g. http://www.modemsite.com/56K/voice.asp

[jsiv]

Adding support for it increases the complexity and cost of the hardware. It's as simple as that. Not enough people care to warrant it. The more recent modems I had years ago did let you plug a headset directly into the modem though, which gives you some of the functionality even if it doesn't work through the computer. Doesn't yours?

[RandFan]

So attach your PC to the phone line using an appropriate connection? You would need a D/A converter of some sort so that the line voltages etc. are correct for the phone system. If you had that small bit of hardware then sure, you could use your PC as a phone. But why? You would still need to subscribe to regular phone service and skype is super cheap and has video!I have a package plan with my carrier. Skype would just be an additional cost.

I guess I'm asking "why not"?

[RandFan]

Adding support for it increases the complexity and cost of the hardware. It's as simple as that. Not enough people care to warrant it. The more recent modems I had years ago did let you plug a headset directly into the modem though, which gives you some of the functionality even if it doesn't work through the computer. Doesn't yours?I can buy a phone for near nothing. How hard could it be? I'm guessing that there is something that I'm just not getting. I have an inexpensive phone sitting next to my computer and you are telling me that the two are so different and a device that would allow the computer to work as a phone is just too much of a headache? Well, I guess the proof is in the fact that it doesn't seem to exist.

Ok, it seems like such a no brainer.

[jj]

I can use my computer and modem to dial but to talk I have to pick up the handset and talk through the handset. Why can't I talk through the computer using the headset like I could with VOIP?

POTS is a wire line (analog) to the office. You'd have to connect your phone line, etc, dial with your modem (it's possible) then take the digitized handset data, turn it back to analong and send it over the wire line.

It's not impossible, it just doesn't make much sense to do.

[RandFan]

The more recent modems I had years ago did let you plug a headset directly into the modem though, which gives you some of the functionality even if it doesn't work through the computer. Doesn't yours?No but I'll look to see if I can find one.

I have to make a lot of calls. A lot. One thing that would be cool is to have the music lowered or muted when a call comes in or I make a call. The other is that all of the phone numbers are in a database. I can currently use the database to dial but I then have to pick pup the hand set it down with my headset plugged into the handset. I can't find a single phone with a headset jack on the base. Talke about idiotic design.

BTW, for years I had Vonage. It was ok but nothing to shout about. At times I had poor quality and lost a call during a tech support session. POTS and even my cell phone are better IMO.

[mummymonkey]

You used to get voice modems that did this with appropriate software but they were a real pain. With some you couldn't listen and talk at the same time.
Spent many a long day on the phone to some Dutch guy when I worked as a PC tech trying to get them to work in customer's homes.

[RandFan]

POTS is a wire line (analog) to the office. You'd have to connect your phone line, etc, dial with your modem (it's possible) then take the digitized handset data, turn it back to analong and send it over the wire line.

It's not impossible, it just doesn't make much sense to do.Ok, thanks, though I'm at a loss as to why it doesn't make much sense to do so. I'll take your word for it.

[jsiv]

I can buy a phone for near nothing. How hard could it be? I'm guessing that there is something that I'm just not getting. I have an inexpensive phone sitting next to my computer and you are telling me that the two are so different and a device that would allow the computer to work as a phone is just too much of a headache?
The "difficult" part is getting the sound to and from the modem.

It requires additional hardware and software to encode the sound in some binary (digital) format on the PC side, transfer it over whatever interface the modem is connected to (usually a slow serial port), and then have the modem decode it and convert it to an analog signal suitable for sending over the phone line. To get sound back to the PC, you have to do the same but in the other direction. This was pretty demanding and expensive back in the day when modems were popular.

That conversion process is not needed by a normal telephone, which in its simplest form is just a microphone that sends different voltage levels across the phone line as its diaphragm vibrates in response to your voice, and a speaker on the other end that vibrates according to the electrical signal received. It's a very simple concept that is cheap to implement.

Having said that, with today's technology it shouldn't be too big of a challenge to make, say, a USB device that lets you do what you want.

Infact, I would be slightly surprised if it doesn't already exist. It might not be marketed as a modem though, and since it's a niche product it might have an artifically high price even if it only costs a dollar to make somewhere in China.

[RandFan]

The "difficult" part is getting the sound to and from the modem.

It requires additional hardware and software to encode the sound in some binary (digital) format on the PC side, transfer it over whatever interface the modem is connected to (usually a slow serial port), and then have the modem decode it and convert it to an analog signal suitable for sending over the phone line. To get sound back to the PC, you have to do the same but in the other direction. This was pretty demanding and expensive back in the day when modems were popular.

That conversion process is not needed by a normal telephone, which in its simplest form is just a microphone that sends different voltage levels across the phone line as its diaphragm vibrates in response to your voice, and a speaker on the other end that vibrates according to the electrical signal received. It's a very simple concept that is cheap to implement.

Having said that, with today's technology it shouldn't be too big of a challenge to make, say, a USB device that lets you do what you want.

Infact, I would be slightly surprised if it doesn't already exist. It might not be marketed as a modem though, and since it's a niche product it might have an artifically high price even if it only costs a dollar to make somewhere in China.:)

Got it. Very helpful and I really appreciate it. MODEM stands for modulate and demodulate. I suppose that I had enough information to figure it out on my own but I just wasn't putting the pieces together. When you add to the fact that VOIP makes it look as if it is doing the same thing it seems that it should be a no brainer when in fact it isn't the same thing (well, it does convert to and from analog and digital signals but it's a different process).

Thanks.

[Lensman]

Some "data/fax/voice modems" & soundcards have an internal connector marked "TAD", thats "Telephone Answering Device", this can be used as - surprise, surprise a telephone answering device.

Now this doesn't answer your query directly, but if you connect the 2 TAD connectors together (there are cables made for this - they often come with the modem), connecting a headset to the soundcard will enable you to use the modem as a telephone, the computer can dial the telephone numbers for you as easily as it can dial-up network.

There were even some combined sound/modem cards available in the dim & distant past, they just weren't very good for games & music.

Even modern modems have mic & speaker connectors.

[Beerina]

I can buy a phone for near nothing. How hard could it be? I'm guessing that there is something that I'm just not getting. I have an inexpensive phone sitting next to my computer and you are telling me that the two are so different and a device that would allow the computer to work as a phone is just too much of a headache? Well, I guess the proof is in the fact that it doesn't seem to exist.

Ok, it seems like such a no brainer.

It's a bit technical, so bear with me.

When a phone talks over good old copper, it's sending some analog signals spread over something like a 3 kHz range of audio. I'm not sure if it translates to that same spread of electrical, but that's the gist of it.

In other words, what the phone sends, dating back to 1900 or whatever, is a bunch of analog electrical waves mapping more or less to the sound wave frequencies you hear.

This is also (one major reason) why phone talk sounds funny -- it chops off frequencies outside this range.


So along comes a modem which wants to transmit digital data. Although digital hardware could transmit electrical flips up and down, on and off, that's not what the phone system was built to transmit.

It must transmit these analog waves akin to sound waves. So the modem instead of trying to flip the electrical on the copper high and low, i.e. digital, pseudo-encodes the digital data as analog data. Since this analog data represents audible frequencies (to phone hardware) that's why you hear those distinctive modem beeps and boops while connecting -- that's literally the modem converting digital data (ones and zeroes) to analog waves.



Ok so far? Ok, next up. Why can't your modem do both and allow you to talk to the headset?


Well, what would that mean with respect to what we know about this? Well, you couldn't do both simultaneously because you get one phone call at a time -- either to a person or to another modem, but not both.

Ok, you think. I have to hang up the modem so I can then use my headset to make a normal call through the modem.

Now that would need the modem to be able to encode and transmit your voice. But the hardware between the modem and the computer is digital. It's the modem that converts the digital to analog to broadcast over the phone.

So your computer would have to take the digital voice data (provided by the analog mic, but converted for you into digital by your audio card, like Souldblaster) and then alter it in such a way that, when it fed this altered digital data into the modem, the modem regurgitated the electrical analog signal that would represent your voice.


And here's the trip: The modem-to-modem communication has it's own rules, and they don't look anything like a phone-style signal. So your modem is (probably) incapable of spitting out arbitrary analog waves, and, more importantly, arbitrary normal-looking sound-style signals. It's limited to beeping and booping.

If it could do arbitrary wave output to copper, then yes, you could write software to convert the digitized data from the mic to the digitized data the modem wants, in order to trick the modem into outputting normal-looking analog phone signals.

But if it can't (which I think) and it's limited to properly formatted modem-to-modem audio protocols (the beeps and boops) then you couldn't force it to output a smooth phone-like analog signal no matter what the digital data you threw at the modem.


It would be like trying to load a baseball pitching machine with specially weighted baseballs in order to print a Mona Lisa in the dirt behind home plate.

[69dodge]

I have to make a lot of calls. A lot. One thing that would be cool is to have the music lowered or muted when a call comes in or I make a call. The other is that all of the phone numbers are in a database. I can currently use the database to dial but I then have to pick pup the hand set it down with my headset plugged into the handset. I can't find a single phone with a headset jack on the base. Talke about idiotic design.

You can buy a regular phone line splitter (http://www.pccables.com/02300.htm), open it up, and rewire the two jacks internally to be in series instead of in parallel. (This way, if the splitter is plugged into the wall, and two devices are plugged into the splitter, both devices need to be off-hook for the phone company to see the line as being off-hook.) Then, plug your modem into one jack of the splitter and your phone into the other, put your headset on your head, and keep your phone off-hook all the time. Now your modem can dial and hang up by itself.

In the attached image, the original parallel wiring is on the left and the new series wiring is on the right. On each side, the '1 2' at the top is the single plug, and the pair of '1 2's at the bottom are the two jacks. (Each plug/jack has two wires, labelled '1' and '2'.)

[Rolfe]

You know what? This forum is really educational. I had no idea about this subject at all, but now I've learned quite a lot just reading through the thread.

It makes me feel a bit better about my own basic-level queries about this and that!

Rolfe.

[richardm]

Just on this:

I can't find a single phone with a headset jack on the base. Talke about idiotic design.

Possibly not, but what you can get are headsets that have a base that both the headset and handset plug into, and then the whole lot plugs into the socket your handset normally plugs into on the telephone. You press a button to select between headset/handset when you're in a call. a pricey example from the uk (http://www.shop.bt.com/productview.aspx?quicklinx=45KB) but it gives you the idea.

[plumjam]

Simply bore a hole in the bottom of the pots. Then knot one end of a long string. Thread the string through the hole in the pot. Put the other end of the string in the bottom hole of another pot. Then knot the string. Try to keep the string as taut as possible, and shout into the pot rather than talk. Listen carefully for a response.
Like Skype it's free too.

Glad to be putting the E back into JREF.

ETA If you neglect to remove any plants from the pots the above process will not only be more difficult and messy, it will also prove ineffective as a reliable communications device.

[uruk]

First OMG!!!! You are still on dial up?!?!?!??! O.K. now that that is out of my system.

You have a few options but unfortunatetly you can't use the POTS line at the same time for dial up and voice for the reasons mentioned by beerina. You are only allowed one connection per line.

So the solutions are:
1. Get another phone line.

2. Upgrade to broadband. I live in a rural area so I don't get DSL or Cable broadband and I can't afford satellite boradband. I do have wireless broadband. They put a microwave dish on your roof and hook you up. It's affordable. A bit more than dialup but less that DSL and cable. The bandwidth is significantly more than dial up but a bit less that cable. closer to DSL speed.

3. Get a cell phone.

4. You can use some software like Callwave. http://www.callwave.com/landing/internetAnsweringMachine_L1.asp
But its just and answering machine.

5. Enter in to an parallel universe where the phone system is wired to support both a data and voice line simultaneously.


Hope this was helpfull