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Remember how back in the old days we would connect two computers with a dial-up to play network games? “Command and Conquer”, “Descent” and “Warcraft" come to mind for example…

Today, we have ADSL modems who are way faster than the 57,600 b/sec modems we used to have.

Everyone is connected to the Internet today, sure but is it possible to connect an ADSL modem to the Public Switched Telephone Network ('PSTN') and connect to another DSL modem, up to thousands of miles away, without paying for more than ordinary phone service, without paying for DSL?

K7AAY
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Ted
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  • Look into a NULL modem. It was basically a telephone cable that could be used like you mention – Eric F Jan 15 '15 at 18:43
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    This question appears to be off-topic because it is not about actual problems that you face. – Arjan Jan 15 '15 at 18:49
  • No. See last paragraph of this answer: http://superuser.com/questions/490797/capture-data-that-my-adsl-modem-send/490899#490899 – sawdust Jan 15 '15 at 18:55
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    So you want to plug your LAN cables into modems instead of just using a single LAN cable going form NIC to NIC? What's the point? – Ƭᴇcʜιᴇ007 Jan 15 '15 at 19:17
  • Are the systems close to each other (like in the same room) or you want to go through telephony network. Note that some of the telephony (voice) networks today are actually IP based. – Mahdi Jan 15 '15 at 19:32
  • @Ƭᴇcʜιᴇ007 I think you meant a "cross" Ethernet cable. Or, he can use an Ethernet hub or switch with two normal Ethernet cables. – Mahdi Jan 15 '15 at 19:37
  • @No I meant a LAN cable, as I wasn't being specific in my comment. ;) Regardles sof that, ["Crossover" LAN cables](http://en.wikipedia.org/wiki/Ethernet_crossover_cable) are pretty much legacy. The Gb spec even includes auto-crossover in the NIC, so every Gb NIC should do the crossover for you automatically (if needed). :) – Ƭᴇcʜιᴇ007 Jan 15 '15 at 19:41
  • 1) You can still get a 56k modem, they even fit in those tiny PCI-e slots on your motherboard. 2) I'd say the modern equivalent is to use hot spots though. If you can't find a free hot spot nearby both locations then you probably aren't looking hard enough. – krowe Jan 20 '15 at 06:53

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Sorry, but no. DSL and ADSL use frequencies to carry the data which are above the frequencies which ordinary phone lines will carry. Special conditioned lines without load coils must be used, and those lines, when they reach the Central Office, are hardwired to strip off the frequencies used for data and do not allow that data to connect to the Public Switched Telephone Network (PSTN), i.e., the phone system. Therefore, you can't use them as if they were a phone modem; if you need a phone modem, use a phone modem.

Anyway, for gaming, you would not want ADSL, which is Asymmetric. Ordinary (Symmetric) DSL (same speed in and out) is far better for gaming.

If the PCs were within 100 meters of each other, you could skip the ADSL modems entirely and use a crossover LAN cable to connect the computers directly, or use a pair of cables, each no more than 100m long, connected through a hub or switch.

If you need to connect over a distance exceeding 100m, then do the latter; add another 100m cable and another switch to extend the signal, up to a total of 500m without paying telco and without DSL devices of any kind.

Why no longer than 500m? A limit built into Ethernet, sometimes referred to as the 5-4-3 rule: In a network where signals can interfere with each other (the 'collision sense" part of Ethernet), you can have a maximum of 5 segments of bare cable, with up to four switches serving as 'repeaters' to clean up the signals, and no more than three of those switches can have PCs (or other devices) on them, for a signal from any part of the network must reach all of the network in time before it expires.

K7AAY
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  • I need this to work without any internet connection, even maybe use a different protocol (other than TCP/IP). I would like the solution to work between modems, P2P. as I see it your answer suggests this is only possible with a DSLAM on one end? The idea was initailly to not need any ISP, no money paid to anyone to be able to connect two remote computers, even if they are overseas. It was possible back at the day. from what I read, ADSL is not capable of long distances? – Ted Jan 15 '15 at 23:17
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    @Ted - *"no money paid to anyone to be able to connect two remote computers, even if they are overseas"* -- Where are you, and how do you expect to get free phone service? Or are you accustomed to your parents paying for such things? – sawdust Jan 15 '15 at 23:59
  • :D sorry, I should rephrase, I would like to do that regardless of the internet connection. no money be paid for ISP's. like old times BBS's. sure, a basic phone service should suffice. as I now see it, ADSL's are only good from the client residence to the nearest phone company's switchboard? – Ted Jan 16 '15 at 18:40
  • Sorry, no go. See revised answer above. Also. please select the complete answer you find most accurate and click on its checkmark. This promotes the best answer and provides a very minor reward to the person who volunteered their time to provide than answer. – K7AAY Jan 16 '15 at 20:28
  • I go into some detail about how DSL works here: http://superuser.com/questions/265163/how-does-the-isp-determine-the-correct-speed-for-my-internet-plan/265176#265176. Basically, your method to the outside is the logical addressing provided by the IP layer which runs on top of ATM. – MaQleod Jan 17 '15 at 00:02
  • Also, don't use a hub - ever - there is no reason unless you need port mirroring for captures. Also, you probably don't need a crossover cable - most devices have auto-mdix to do the pair switching for you. – MaQleod Jan 17 '15 at 00:04
  • Lastly, sdsl is getting harder and harder to find, and is usually expensive if you do manage to find it. It is often linked with business needs and is treated often as a poor man's T1. It is usually fairly limited in speeds as it is a really dated technology. You're honestly better off with adsl2+ (or vdsl if you can get it). – MaQleod Jan 17 '15 at 00:12
  • This answer's awesomeness would go through the roof of it included an explanation why you have to [stop adding switches](http://en.m.wikipedia.org/wiki/5-4-3_rule) once you reach 400 meters (technically, 500m) in total cable length – I say Reinstate Monica Jan 18 '15 at 01:49
  • If you don't want to depend on an ISP, really your only option these days is wireless mesh networks, i.e. https://projectmeshnet.org/ – LawrenceC Jan 18 '15 at 01:50