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I was thinking the following: A lot of phone companies give you a couple of phone numbers that you can call for free.

Suppose we have 2 mobile phones:

P1 = Phone 1
P2 = Phone 2

P1 have free calls to P2

  • We take P1 SIM card and connect it to a computer SIM reader.
  • We do the same with P2.
  • Now we can call P2 from P2.
  • This means we can send any kind of data in such call.
  • Then we can tunnel an SSH protocol through the call so we call access P2 computer from P1.


  • P2 is connected to the Internet somewhere.
  • P1 is in the middle of the desert.
  • P1 calls P2 and now P1 have access to the Internet through an SSH tunnel!



Do you think this is possible?



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Only as slow as a Dial Up connection, is not that bad (?) – Zequez Oct 25 '11 at 13:49
free != constantly connected. – Sirex Oct 25 '11 at 14:03
A call means you have to use the plain old modem emulation. Therefore you get max. 14400 bits/sec on GSM. I think this is what Michael K was pointing out. You won't get a regular data connection like GPRS/CDMA between two phones. – Robert Oct 25 '11 at 15:16
To make that clear, what I wanted to say is, that you bandwidth would be very low (a bit below GSM or whatever connection you use), which is not very much in any case. The ping time would hardly depend on your location. If you only want to send some text somewhere, there will be a better way using you regular phone features and for anything else, it would not be very satisfying I guess. What do you want to use that for? – Michael K Oct 25 '11 at 15:25
IDK, the ping would be more or less the same one would have in a mobile phone conversation, is not more than half a second. And with the speed concern, well, at least you could do some web browsing without images right? Also you would have access to chat communication services like Facebook Messenger, email, and stuff like that. Better than nothing I guess :P – Zequez Oct 25 '11 at 16:20
up vote 2 down vote accepted

Warning: This will be entirely conjecture. I once had a conversation with the Verizon help line about a cell problem I was having. While on hold I noticed their music kept cutting out and getting garbled. In the past I had heard the same thing with other hold music. Asking the help representative about it, he said that they use compression to reduce the call bandwidth on their system and noise cancellation to avoid street/wind noise from coming over the line to improve call quality.

If this is the case with all cellular providers, your data will most likely get corrupted in transit. Probably conquerable but you would need alot of parity bits reducing your overall bandwidth to practically nothing.

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I think, but could be wrong, that the GSM dialup standard (if there is such a thing) could have some sort of check sum code to make sure that if your data is garbled, it will re-transmit it... you, in theory, wont actually loose anything, but it may be a lot slower... I have also noticed this effect on Vodafone Ireland, and some of the other networks here too... – TiernanO Jan 25 '12 at 8:50

It would be posible to do this:

  • using a PC, you can accept phone calls from a modem (phone 2) and initiate a network connection.
  • once the connection is open, the phone on the other end gets an IP address
  • using that IP, and the "server" ip, create your SSH connection

Couple of things:

  • the Phones themselves probably wont have the hardware to do this, you will need to do this with the help of a couple of PCs (laptops or desktops).
  • as has been mentioned, speeds will be slow (9.6k - 14.4k for some GSM devices)... and thats assuming your connection is stable...
  • again, limits on what you can and cant do with your calls (an Irish Mobile Operator is offering "unlimited" Calls, but have it set to 45,000 min a month (which is more than the amount of min in a month). but others may not be so willing to give you unlimited calls).
  • also, the mobile internet operators will NOT go bankrupt. They will either figure out a way of "fixing" (i.e. terminating your contract or some such) your new fangled way of getting a really slow internet connection, or give you a better deal over GPRS or HSDPA . remember, 14.4kbits/s over the course of 30 days is less than 5Gb... if your provider gives you 10Gb, you can use 28.8Kbits/s for the month without ever hitting your limit.
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Yes. What you are describing is dial-up internet, albeit with a mobile connection instead of copper wire between you and the ISP (P2).

Just because it works doesn't mean it's a good idea, however. As others have pointed out at length, you wouldn't get much bandwidth - dial up normally topped out at 56kbps, and you'd probably get less thanks to your mobile connections. Also, you will often find that free calls to n numbers offers tend to put a limit on the maximum length of each call you can place for free, although you can immediately re-dial and re-start the free clock. The telcos can be quite open about this - I have even been instructed, entirely unsolicited, that re-dialing every hour was a valid strategy for avoiding any charges by the salesman while ordering a phone line, so I suspect the reason for the limit is to stop people just leaving a phone off the hook (either accidentally or deliberately to use it as talkback or to do something enterprising like this) and hogging a connection.

If you really needed to do this, there are solutions - such as mobile broadband - that provide a far better ratio of cost to convenience and reliability, if not lower cost overall: the phone call may be free, but the line rental probably won't be (especially if you're getting free calls) and even PAYG phones will probably expect you to top up every few months to keep the number connected. You also need to own and operate P2 (and its internet connection), rather than just connecting straight to the internet from P1.

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