Home phone wireless upgraded modem to 4G. Cannot receive or make calls.

Sounds like it hasn't been activated. See this topic and the links in it.

Thanks spoom2.  I think the path you are suggesting presumes we have an ATT Internet acct which easily enables using each link provided by ATT in the ATT How-To.  I'm sunk without ATT Internet, so evidently I will be finding a different phone to reach ATT 800 331-0500 number to resolve this.  (ATT is saying most of their devices are activated as sold.)  This new modem's package includes a card "Activate now", English one side, Spanish the reverse.  It refers us to att.com/getstarted which seems to require an active ATT Internet account.  I tried to duplicate the "Getstarted" link on my laptop's Internet, and that's a dead end.

The information is from customers like you who've said it works.

OK, it took a trip to my local ATT store with my new IFWA-40 modem where they discovered my acct still had the hardware as the old LG modem.  ATT did not know I had installed the new IFWA-40 modem.  The manager replaced its SIM card which removed whatever was blocking incoming/outbound calls on my wireless home phone.

I asked them if I been more resourceful, could I have solved this problem via ATT 800 phone numbers?  He replied "No, this issue needs to have direct attention at an ATT Store."  Happy camper now.

Thank you for the update, EL51203phoneHELP.

We are happy to hear that your modem is back up and running, and that your phone is able to make and receive calls.

If you have any other questions or concerns in the future, feel free to reach back out.

Thank you for choosing AT&T.

Marc, AT&T Community Specialist

@EL51203phoneHELP We had another topic where the user had to take the unit to an AT&T store. Seems like there ought to be one way to do this instead of several. 

@EL51203phoneHELP Approximately what date did you obtain your IFWA-40?

AT&T notified me they stopped supplying this product on 12/7/2021 so they are refusing to upgrade my 3G wireless home phone and allow service continuity. Please advise whether yours was ordered before or after Dec 7.

Their original post was 2/18/22

Hi jepherey - My IFWA-40 arrived from Ft Worth TX 3rd week August 2021.  The packaging was way too premium.  Subsequently at least 3 AT&T letters arrived to remind me to hook up, a couple in early Dec and the last of which was 02 Feb 2022.  So I finally hooked up.  Then the fun began.

Thank you for the clarification.