finding account number

Your wireless account number is indeed in your online account. If you are having trouble getting access to your wireless bill and are only seeing your home services, call AT&T and ask for assistance to log into your wireless account. 

FYI you don't need your account number to access your online wireless account, just the primary phone number and your billing zip 

https://www.att.com/support/article/my-account/KM1008921/

You should be able to link accounts after that 

https://www.google.com/search?q=creating+a+AT%26T+access+ID+to+link+wireless+account+to+existing+Internet+account&oq=creating+a+AT%26T+access+ID+to+link+wireless+account+to+existing+Internet+account&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCDY0MzdqMGo3qAIUsAIB&client=ms-android-oneplus-rvo3&sourceid=chrome-mobile&ie=UTF-8

Actually, if you enter phone and billing zip, the next page asks for you account number to verify you should have access

This is what comes up

Hi @SCsteelerfan, we understand the importance of knowing your account number/details. Let's guide you in the right direction. 

The Community Forums are a public support option where other users, and AT&T, will try and assist with high level support needs. This means we won’t be able to look into account specific concerns. To get the help you need for your unique issue, please review our Contact Us page, and choose the best option to reach out to us. You can call, chat, or reach out via social media and we can review your specific issue and provide you support. If you feel your issue isn’t account specific, and can be answered generally, please let us know and we’ll be happy to help.

Thank you for visiting AT&T Community Forums. 

CrystalS AT&T Community Forums Specialist.          

Hmm that's not right