$50 off $50 AT&T Business Fiber successfully used on residential internet. I think I read/did this strategy in the last 6-18 months, but just reconfirming for others. Did this yesterday.

https://www.business.att.com/login-portal.html
"Pay without signing in (Premier & MyAT&T)"
Should lead to https://www.att.com/acctsvcs/fastpay?smbContext=true
Payment triggered as "AT&T HSIA BUS E-EVR"
Amex offer email confirmation within 24 hours

Edit: This also ended up triggering the $10 monthly business platinum "wireless credit"