Yep, have done the charge/discharge. It comes with 2 batteries and neither will get beyond 6 hours.
When one does a check command, it sends an SMS advising GSM is on and GPRS is off. I was thinking of turning GPRS on and then off.
I think GPRS is off as I only get billing on the mobile account when I request an SMS from it.
I'll fire off an email to the vendor today.

