[Gllug] Modem emulator

damion.yates at gmail.com damion.yates at gmail.com
Wed May 12 01:05:02 UTC 2010

On Mon, 10 May 2010, Andrew Back wrote:

> On (13:06 10/05/10), Matthew King wrote:
> > The scenario:
> > 
> > Home network's fancy router has a (56k) modem on it plugged directly
> > into the phone line (actually it doesn't but the fact that Martin
> > has one reminds me that I ought to get one).
> > 
> > While out, the house's connection to the internet breaks for
> > whatever reason. Hoping it isn't the router itself, I pull out my
> > mobile phone, dial my modem's number and ... hear screeching because
> > I don't have a modem on this end.
> > 
> > Is there software available which can use the mobile network to send
> > modem traffic? Is the codec even capable of it?

Phones that still support pre gprs can call at up to 14.4k over gsm
data, last I saw O2 were dropping the channels down limiting back to
9.6k, I complained but nothing came of it.  By this time gprs was taking
hold.  Orange were the only ones bothering with the even more advanced
hscsd (up to 43k), I don't know how many channels this ate up but it
couldn't exceed 28.8k in the mode that worked with them (my phone
mentioned analog 28.8 or digital 43 and various speeds up to those on
either a/d?).  Over in Europe you could get full speed hscsd, and even
EDGE on gprs which did't take off here until many many years later when
the tech was just about dead but Apple decided to launch the iPhone.

I've a feeling my n900 can't support this, nor the many Androids or
iPhone.  My symbian N97 can.
> GSM also has "circuit switched data" (as used mobile IP access
> pre-GPRS) which could give you a 9.6k connection, but I'm pretty sure
> that the fixed modem would have to be in the GSM network. I could be
> wrong...

I believe you are.  I was able to call modems in the terminal app on the
older Nokia communicators, or establish a ppp connection if it was
expecting one.
I had planned to put a modem on my own network, but I don't leave a PC
with PCI turned on (I only have some old pci card modems spare).  I
haven't yet bothered paying for a usb or old-school external serial
connecting modem.

My main aim was in-contract minutes for the call for the times gprs dies
(very rare occasions in busy pubs in central london during football
matches).  I'd then route out over my adsl.

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