We have now received confirmation on that AT&T has managed to resolve the issue and we are no longer observing any intermittent DLR issue since 2019-12-22 08:45 UTC.
Posted Dec 22, 2019 - 09:07 UTC
Update
We are now observing intermittent issues with DLR coming back from AT&T US. There is still a remaining potential for MT and MO impact as well.
Their Engineers are still working to resolve this as quickly as possible.
Posted Dec 22, 2019 - 08:25 UTC
Identified
AT&T Engineers have located an issue within one of their SMSCs and they are working to resolve this as quickly as possible.
So far there has been no observed impact for the services, however there is still a potential for delayed message to and from AT&T US.
Posted Dec 22, 2019 - 06:50 UTC
Investigating
We have received alerts that may indicate potential delay towards AT&T US. You may experience delays with SMS MT, MMS MT & MO's
We are working with the operator to resolve this as soon as possible
Posted Dec 22, 2019 - 03:49 UTC
This incident affected: External Connectivity (SMS - US - ShortCode, MMS - US).