Which GSM module ???
We have used wavecom in devices, that working far from city, in the field, inside metal boxes, all seasons, as unnattended data aquisition module.
After two year uninterrupted exploitation from
20 devices, all modem continue work, without
malfunctions. Device measures temperature on
main chip, and it was from -33 to +65.
Metal boxes, where placed devices not hermetical, and case of device has rubber gasket, with gaps,
we saw tracks of water leakage and unfrozen
on case of modems and pcb of devices , but
modem remain good work. What else need for reliable device?