I currently have an AT&T plan “Access for iPad 4G LTE” for $20 ($23.49 w/fees). This plan I got in the store. It includes 22 GBs of LTE, but I have done 100 GBs, but anything over 22 GBs might slow down if the tower is congested.
Yep, if you have an AT&T-postpaid account, it's a pretty good deal. The prepaid version is mostly dead outside of some grandfathered users. It also seems they've been enforcing IMEI checks to make sure the SIM is in an iPad.
Personally, the T-Mobile $10 pre-paid/one-time deal is what makes a cellular iPad worth it for me. I don't use a lot of cellular data but I can burn through a lot when I need it. Great value!
I've used this plan more times than I can count—currently on a Wi-Fi-only iPad, but have used it on a previous 5th-gen, my work iPad Pro, and a prior original 12.9" iPad Pro. Even though it's billed as one-time, you can purchase it multiple and it's perfect for not much data. Technically, it's for a few select iPads, but the data should flow to most devices. I actually had a SIM with it on there and put it in my iPhone 11 when I visited Canada—it roamed on Telus, while my main service at the time roamed on Rogers.
In my area, there’s a data service provider called Truphone.
They offered a free service trial directly on my iPP, on my iPhone at the moment or would have a screen handy.
Anyway, they do piggyback off T-Mobile but have some nice plans that the big guys couldn’t match.
will pop pack here.
Not sure what area you're in, but like GigSky, they're typically designed for passes for global roaming. I think there's a few that are in a sweet spot, but many are more expensive than recurring prepaid plans. Airalo (not sold through the iPad interface, uses Truphone's back-end on some plans) is another that might interest you if your iPad has eSIM—roams on T-Mobile and Verizon in the US, but is technically intended as a global travel option.
I like Truphone for their prepaid voice SIMs—$30 to get started, and $15 of that goes as a credit. In the US, they roam on AT&T and incoming calls/texts are free. Data is a bit pricey so I disabled it, but it's a nice way to keep "service" on some older devices or park a number.