I have T-mobile I like it too but it don't work with a SIM900 On the flip side tho It will get the right stuff back show the thing has network sig and is on T-Mobile
But when I send a text it don't send I show it has a working number.
I'm have a play with it soon and try something I just read that maybe get T-mobile to work.
I'm currently sat about a foot away from a SIM800L module, it's connected to a PIC 18F26K22, which is reading a DHT22 sensor, displaying the temperature as a graph on a TFT module, and sending the temperature and humidity data via GRPS to a MYSQL database running on my website. At the moment this is pretty well a 'proof of concept', in particular I'm wanting to find out how much it costs to do this - but the answer seems to be very little - the 'standard' way of doing this sort of thing was via txt messages, but that is pretty expensive, so GPRS looks to be a LOT cheaper. It ran for 8 hours the other evening (until the battery went flat, I was making no effort to conserve battery power), and uploaded data every 5 minutes - I checked the credit on the SIM card (in fact I checked it on two cards, as I'm not sure which one I'm using
) and after 8 hours the credit (on either) hadn't changed. Checked the details of the service provider they charge 5 pence per megabyte, and 5 pence per txt, so it's vastly cheaper via GPRS as I'm only sending a few hundred bytes (if that?).
Incidentally, we have a number of 'loggers' out there for customers, that send back weekly meter readings via txt messages - which we have to 'top up' the credit for every now and again. They also require occasional battery replacement, which are 2 x ER26500 Lithium, with a 'BEST' capacitor across them, as they have quite high internal impedance and can't supply the high current pulses required by the GSM modem.
This talk of ending 2G, and even txt messaging, would cause an awful lot of chaos - as there's
HUGE numbers of remote devices out there, most of which use either txt or 2G.
What do smart meters use?, are those 2G?, 3G?, any G?, or even txt messaging?.
BTW, here's a picture of my test setup, on a JLCPCB board - the small chip above the modem is a dual FET, used to switch power to the modem board, so it can be completely turned off for power saving. The missing SM IC is for an I2C memory chip.