I'm based in Africa and have deployed a number of devices that make use of SIM800 or similar breakout boards. No matter what provider I use in any country, APN "Internet" has always worked to get the modem connected to GPRS.
I just sent a unit to the US and I did not really think about this issue, but now the unit is there with an AT&T SIM in it, and it is not able to get onto GPRS.
When looking around for APN details I found a bunch of different APN's, none of which is "Internet."
And the user told me that AT&T sales people told him that a normal SIM won't work since it needs to be linked to the mobile device. When he told them its for an IOT device they went blank.
What's the solution, what do you guys in the US use? The user only has AT&T coverage where they're at.
I am nowhere near an expert, but did some Googling and came up with this. It's from acompany (Emerson) who supplies trackers to the trucking industry. Apparently the USA is shutting down 2G AND 3G (soon). And of course the problem with 4G is that frequencies are not universal.