We've got the GW Mobile server and SGW up and working. However, all is not
rosy in the garden!

Is there a "keep alive" option for the devices when they are connected via
GPRS or 3G?

Perhaps a hidden parameter somewhere or a method that we could use to
increase the the time before the communication "tear down" takes place.

Would this be controlled by the air-time provider perhaps?

Any suggestions would be appreciated.