[SGVHAK] The Modem Challenge

[Braddock Gaskill]

I've been informally trying to get a software modem to work at 300 baud,
figuring I'd use a microphone and headset to make a poor man's acoustic
coupler to a cell phone (or skype or anything).

The closest thing I've found is minimodem, but it is not full duplex. 
Probably can be hacked.  The HAM stuff like fldigi could do it but again
only half duplex.

I tried hacking sl-modem-daemon, a generic soft modem driver, to get it to
work with a standard ALSA sound device (instead of a WinModem), but I
couldn't make it work after an hour or two - it relies on a 32-bit closed
source DSP library and is pretty well hard coded to certain bit rates.

-braddock

On Fri, 11 Jan 2013 15:30:20 -0800 (PST), Lan Dang <l.dang at ymail.com>
wrote:
> I came across this webpage that seems to involve true 
> hardware hacking--I saw instructions for soldering--in order to hook up
a
> modem to a cell phone.  I'm not entirely sure I understand the purpose 
> or feasibility of this hack, but the comments are interesting.
>
http://everything2.com/title/How+to+connect+any+cellular+phone+to+a+modem
> 
> 
> 
> Anyway, here are some notes and links I have gathered.  This is not an
> easy subject to look up as most of the time, the conversation and
> instructions are about mobile tethering and 3G modems.  Also a lot of
the
> relevant conversation for dialing out to other modems tends to be from
2007
> and earlier, back when the desire was more common.  Sometimes, I look up
> faxing.
> 
> 
> I think it boils down to:
> 1) Carrier must support it.  It was easier with CDMA for some reason. 
It
> could be that the CDMA carriers had more of a customer base interested
in
> this technology.  (People usually reference Sprint.)  Or it was easily
> supported in the underlying technology.   These days, it's unlikely that
> the carrier supports it because they have moved away from something
called
> cct switching.  (I think they're referring to circuit switching)
> 
>
http://www.computerweekly.com/feature/Sprint-moves-to-packet-switch-network
> 
> 
> 2) Cellphone must support it.  If the modem capability isn't built in,
> then you have a problem.  I think the newer phones are data-only, but
you
> might have luck with some older phones.  I think there was some talk
about
> using old Nokias for this.  It may be a combination of hardware and
> firmware.  "At least some phones (those that maintain 
> compatibility with old network protocols) have built-in modems that 
> respond to AT commands.  If you have one of these you should be able to 
> connect to a modem elsewhere in the phone network."
> 
> 3) Drivers and/or connection software
> Basically, you need a way to hook the phone up to your computer in such
a
> way that it treats it as a modem.  This can be done over Bluetooth or
> directly over USB, but it may require drivers or some kind of special
> software.
> 
> I think these days, when you connect your Android phone to a computer, 
> it's with the expectation of data transfer or tethering, so other
services
> are unavailable.  i don't know if rooting or flashing the ROM would
help.
> 
> 
> REFERENCES
> Fax over a GSM Cellular Phone (2001)
> http://navasgroup.com/attwireless/fax.htm
> 
> Engadget 2005 article
>
http://www.engadget.com/2005/01/18/how-to-use-your-cdma-cellphone-as-a-usb-modem/
> 
> Lifehacker 2006 article - 
>
http://lifehacker.com/175048/geek-to-live--use-your-cell-phone-as-a-modem 
> 
> Courtesy of Wayback machine, instructions for GSM modem using Mac (circa
> 2006)
>
http://web.archive.org/web/20120417183025/http://homepage.mac.com/jrc/contrib/tzones
> 
> QNC And Dial-up Compatible Phones (not sure if this is for analog
dialup)
>
http://wiki.howardforums.com/index.php/QNC_and_Dial-up_Compatible_Phones_and_HowTo
> 
> Useful forum thread on this topic from 2004:
>
http://www.velocityreviews.com/forums/t3953-dial-up-through-a-cellphone.html
> 
> Other Forum postings
> 
>
http://forums.cnet.com/7723-7584_102-21639/connect-laptop-via-dial-up-modem-over-a-cell-phone/
>
http://superuser.com/questions/355241/how-can-i-use-my-cell-phone-to-establish-a-dial-up-networking-connection
>
http://www.linkedin.com/answers/technology/information-technology/computer-networking/TCH_ITS_CNW/783279-76546455
>
http://forums.cnet.com/7723-6142_102-234705/cell-phone-as-a-modem-for-a-faxing/
> http://www.tomshardware.com/forum/2564-37-cell-phone-analog-modem
> 
> Modem scripts for Mac
> http://www.taniwha.org.uk/
> 
> 
> Lan
> 
> 
> 
> ________________________________
>  From: Braddock Gaskill <braddock at braddock.com>
> To: Hardware Hacking Special Interest Group <hak at sgvhak.net> 
> Sent: Friday, January 11, 2013 9:17 AM
> Subject: [SGVHAK] The Modem Challenge
>  
> 
> Hi folks,
> 
> So as you know I've put up a BBS (626-441-2970), but it seems that most
> people no longer have access to the technology needed to access it. 
Very
> sad.
> 
> So I'd like to challenge the group to find a solution.  Can you dial in
at
> 300 baud over a cell phone?  Or without a modem?
> 
> This could be a real public service for, for example, political
dissidents
> when a nation's broadband goes dark.  And it sounds like fun.
> 
> -braddock
> 
>     ____                       __                            
>    / __ \ ____ _ _____ ____   / /_   ___   _____ _____ __  __
>   / /_/ // __ `// ___// __ \ / __ \ / _ \ / ___// ___// / / /
> / _, _// /_/ /(__  )/ /_/ // /_/ //  __// /   / /   / /_/ / 
> /_/ |_| \__,_//____// .___//_.___/ \___//_/   /_/    \__, /  
>                    /_/   ____                 __    /____/  
>   Dial in, get root     / __ \ ____   ____   / /_            
>   An experiment in     / /_/ // __ \ / __ \ / __/            
>    social SysOps      / _, _// /_/ // /_/ // /_              
>    626-441-2970      /_/ |_| \____/ \____/ \__/