Home phone upgrade to 4G not working, Calls not allowed on this line message

Well, I suppose it could be a site issue. Here's some other methods people used. There're two places to enter your SIM, don't use the SIMe

I had to take my IWFA-40 device to an AT&T store because after spending over 90 minutes on my mobile phone with customer service/tech support to try to activate the SIM card, I was told that they could not help me. The AT&T tech person at the store had to replace the SIM card that came with the new device because it did not match with the ICCID number on the box. At least for now, I have service again. Thank you for all your suggestions. It really helped.

I think you're at least the third person who's said the unit came with the wrong SIM card. 

Thank you for this post.  I have spent hours trying to figure this out and working with AT&T tech via telephone.  The tech's only answer was to go to a AT&T store. What fixed it for me to be able to receive and send calls was to follow the link and activate the SIM card.  Before I did the activation of SIM step, (1)I updated the new device I had associated to my home phone number in my online account; (2)I rebooted my device and plugged in the phone; (3)activated the SIM by following the link; (4) tested phone to receive and send calls.  

Reposting this to make sure it's in here several times so people don't miss it and to put it on the bottom. @cjtaz thanks for letting us know what worked for you. 

 Here's some other methods people used. There're two places to enter your SIM, don't use the SIMe