Fixed IP SIM cards and GPRS

Hi All
Anyone use Fixed IP Sims and GPRS to remotely connect to their machines?
I'm looking at moving from GSM connectivity to GPRS.

1. Does the SIM provider give me a 'VPN' of sorts to access my SIMs?
2. How do I VPN to the provider - do they provide this software?
3. My GPRS modem has a serial port. Will it 'strip off' the ethernetty packet stuff and leave me with what I need? I'm guessing that there's an ethernet to serial gateway built-in; or is this not the norm?
4. Email. Can it?

Particulary interested in UK members, as there seems to be one main supplier of this service over here, so chances are you'd have specific experience of the people I plan to approach.

Cheers
Pp

Hi,

We've used the Insys Modem-Router-Switch recently. It has the facility for a SIM card interface. This could be GPRS or (I'm sure) this one also supported EDGE. There were 2 flavours to pick from. The 'Pro' (approx £100 more) - was able to establish a standard GPRS connection (APN settings etc.) and off you go onto your Ethernet network via GPRS.
The other model was cheaper, but only supported (so i was told) a form of 'open VPN' where you are required to buy into a monthly subscription for a static IP address from a 3rd party (we looked at Wyless) - Typically charging approx £3/4 per month (c/w 1MB data free), or you can pick a different tariff to suit your data needs. You download a bit of free VPN s/w to enable access.
You then need to set up a bit of port forwarding in the modem switch and off you go...

This was only a brief dabble with the modem (we just tested it on the bench) - but it did work. We will soon be testing a couple of others...


Hope this helps.

Rob

1. Does the SIM provider give me a 'VPN' of sorts to access my SIMs?
It depends on the contract you take out, the more the provider does the more the system costs but the less effort you have to put in. For me, the provider just associates a public facing IP address with my modem on his network, then I take care of all the connecting and VPNing to the machine.

2. How do I VPN to the provider - do they provide this software?
It depends on the contract you take out. I prefer to have more control so I choose the modem and so the VPN connection. The GPRS modems that I have researched only allow you to VPN in from one IP address, so I would always have to be at the office to make the connection. I don't use the VPN on the modem but insead place a more flexible router behind it. Then I can set it up so that I can make the VPN connection from anywhere.

3. My GPRS modem has a serial port. Will it 'strip off' the ethernetty packet stuff and leave me with what I need? I'm guessing that there's an ethernet to serial gateway built-in; or is this not the norm?
You need to check the manual but the modems I use come with software to create a virtual serial port on the computer. Then when you connect to a device on the virtual port you are actually connecting to the remote location. The ethernet stuff is tranparent to the thing using the virtual serial port, the only issue can be latency in the communication path, GSM was never designed with Data in mind, it can take over a second for data that is sent before it is receievd.

4. Email. Can it?
The modem may be able to email reports on its' status. The remote device may be able to email but you would have to do some programming to make it happen. I haven't tried emailing from a serial device, only ever from HMIs or Embedded Computers.

I have used Wyless in the UK, they seem OK, though last time I tried to contact them nobody answered the phone and I got no reply to emails.

I did start some brief notes on remote comms but never got round to finishing. This from Digi is worth reading, as well as this.

Bryan

Thank you both for your input.

My modem company have pointed me toward Wireless Logic as a SIM provider, with a quote of about £3 a month, which seems very reasonable to me.
Pp