It appears there is a bug in the SIM900 firmware on the GPRS Shield V2
The bug in question has to do with the handling of time when trying to use the RTC that’s included.
You set the time by using
however the maximum number accepted for timezone is 48 (GMT+12), however NZDT is GMT+13 and while the dates are reported correctly when I pull them from the network with a TZ of +52, you can’t use that to set the RTC. Examples below
Is there a later firmware than whats shipped, or any way to update it if one does exist?