Problems with AT&T Customers Sending Messages

Is anyone else having issues with AT&% customers sending you messages?   I have been on the phone with T-Mobile for over an hour and they have not heard of any issues.  Yet if I do a quick google search, several posts come up, specifically those from AT&T customers reporting the issue.  

https://forums.att.com/conversations/data-messaging-features-internet-tethering/sporadically-my-texts-not-getting-thru-to-tmobile-recipient/659cba0e19f03b1e47f02239?page=1