Thanks for answering all the questions .
Your battery, data, and premium credit situations seem to be good.
You do just need a standard SIM. However, since you are dealing with a defective one, you’ll probably want to talk to AT&T, either at a store or over the phone, once you get the new one. You’ll need the ICCID from the old SIM (that’s available on the AT&T Buy-A-Session web site, but you’ll have to know which one is the bad one) and from the new one.
I’m not sure of the procedure to swap ICCIDs but obviously you don’t want to lose the data on the current SIM. The store personnel know zip about session-based plans, but you should at least be able to get a SIM from a local store. Then you’ll have to talk to someone about changing the ICCID from the old, bad SIM to the new one on the plan. This is going to be the trickiest part, especially being able to talk to someone who is knowledgeable about session-based. Be sure to use the term “session-based” when you start talking to anyone or they’ll lead you down the primrose path for every type of plan except the one you have.
AT&T SIMs are not tied to specific cameras. (Spartan SIMs are, which is why I specifically mentioned AT&T.) In a way, you are fortunate that you have several cameras (as long as they are sort of in the same area) because you can swap out SIMs between a working camera and a non-working camera and tell very quickly whether the problem is the SIM or something else. I have had to do that numerous times. Sometimes cleaning the card (rubbing the gold contacts against your jeans or with a pencil eraser) will fix the problem, but it’s inexpensive to just replace the SIM.
No, there is nothing special about the SIMs in the cameras, other than they are “standard” size, not micro or nano. They’re not for any particular device or brand of devices.
I think maybe there was some miscommunication or misunderstanding in your dealings with both AT&T and Spartan. Here’s hoping you can get a quick resolution now that you know what the situation is.