Walked into an AT&T Store today to signup for the 100GB $55 a month plan. 20 Minutes later I walked out with a sim card, inserted into my Pepwave and surfing away.
I mentioned to the sales associated I wanted to sign up for the 100 GB Prepaid plan, he asked for my IMEI and that’s all it took. It was no hassle they associates new what I needed, I added a copy of the receipt in case anyone needs to show at&t if they neglect to sell you the plan.
I’ve got this and it’s working nicely in my MAX BR1 MK2.
You should be able to get it online with this form without visiting a store. https://www.att.com/prepaid/activations/#/activate.html. That didn’t work for me because it didn’t recognize my IMEI so I went to a store like you did. Now if I try that form it does recognize my IMEI.
If you have a PIN you can manage the account here https://www.paygonline.com. That means monitor usage, pay money to refill it and move to a lower plan if you want to almost put it on hold if you’re not going to use it for a while. To get the PIN you need to receive a SMS message to the router. My Pepwave doesn’t seem to receive texts so I temporarily put the SIM in a phone and that worked.