Always-on networking via GPRS

[Nuutti Kotivuori]

Hi,

One of the first things I'd like to do with my Neo1973 is to configure
the GPRS connection to be always on.

As I've understood, on the GSM level, the GPRS connection gets paused
on text messages and incoming calls - but the GPRS call can still be
resumed. On answering a call or making a call yourself, I take it that
the GPRS call will get disconnected. Did I get this part right? Or is
there a way to keep GPRS alive over voice calls? Or do text messages
disconnect the GPRS connection?

On the actual software level, I guess this means that PPP will get
disconnected on voice calls, so the 'ppp0' device will go appear and
disappear and possibly change IP-addresses on every disconnection as
well. Is there any way to have the device survive disconnections?

I ask this because there's going to be some complications from
that. Firewall is no problem as it can be static, but QoS rules will
need to be re-instantiated on if-up scripts. Also, any applications
binding specifically to an interface will need to be able to handle
the interface going up and down.

My main goal is to have Neo1973 have internet connectivity at all
times - but it would be nice to allow access to the internet via
Neo1973 for other devices as well. However, this should not disrupt
the connectivity for the device itself. So the device has to keep a
private network for other devices and NAT the connections.

USB-networking is probably no problem since it shows up as a normal
ethernet device on both ends. But how to do Bluetooth networking? One
choice would be to do Bluetooth PAN. This would require 'pand' and
modules on the Neo1973 side. The device should be configured as a
Bluetooth NAP, I guess. The other choice would be to use Bluetooth
DUN. This would require running 'dund' and a PPP server on the
device. Bluetooth DUN is quite a common use case for all sorts of
mobile devices - Bluetooth PAN sounds like nicer setup though.

So, I'm asking for input on these issues and I'm interestested as to
how much of this is already available on the device and how much work
would setting all this up be.

Thanks in advance,
-- Naked