I looked into the UK system earlier this year and spoke
with a company rep. Several companies offer a similar
service to track commercial vehicles and manage the
fleet.

Briefly as I understand it, the system here works on
a GPS reciever and logger in the vehicle and this transmits
data via ground cell telephone systems back to base.
The cell phone system has numerous 'spare' channels
not used for the 'phone system. The problem is that
trying to use the cell phone in the air, unless low
down on a ridge, or behind a mountain, causes the
cell phone to shut down.

The basic cost was about £700 for the vehicle kit and
then a further load of cash to get kit to manage the
data.

So at present not practical and expensive