RE: OT: USB 3G modems

["Dave McLaughlin" <dave_mclaughlin@xxxxxxxxxxxxx>]

You could use any USB based GSM modem to do this. The issue you have
is how
you send and receive commands to it.



Even if you get it to dial up by sending an SMS to it, it will not appear
visible on the internet because of NAT and private IP's within the GSM
network. What you are going t have to do is get it to dial up and make a
TCP
connection to some application running at your intended monitoring site.
This way you now have a connection that you can send and receive data
through, but only via the 2 applications.



An alternative idea, which I am not sure will work, is to get the remote PC
to make a VPN connection to your monitoring site. This way I think you
would
then be part of your network and it should be visible both ways. I have not
tried this before so I am not sure if this will work.



Someone else pointed out that your could leave it connected as you only pay
for data, but sadly the PC does a lot of IP traffic and you would see a
nice
bill each month unless you where on a fixed price unlimited package.



Either way, you're going to need an application to listen for the SMS and
make the connection. Not sure if there is anything off the shelf so you may
need to roll your own!



If you could borrow a GSM modem for testing, you could try the VPN idea and
see if that works.



Good luck with it.



Dave.



From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Jon Wilkins
Sent: 25 September 2009 15:53
To: ukha_d@xxxxxxx
Subject: [ukha_d] OT: USB 3G modems





Hi All,

I'm needing to build an unattended linux box to do some occasional remote
equipment monitoring. It will be in locations where there isn't internet or
fixed line but will be GSM and/or 3G. Because it'll be occasional use I
don't want it to be online all the time (waste of on-line cost &
power), so
want to be able to 'activate' it when needed -- ideally by being able to
send it a text or dial in to it to tell it to open it's 3G ( & open an
IP
tunnel to 'home').

Does anyone know if the 3G 'sticks' that the networks are currently
offering
have the ability to receive incoming data calls or texts? [ ie would need
it's own phone number at the very least ]

Thanks,

jon





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