The vendor identified root cause as an incorrect "calls per second" setting at the trunk level, which caused a large portion of inbound U.S. calls to fail due to hard limiting call concurrency. This setting is fixed moving forward.
Nov 21, 12:39 EST
At this time, all numbers should be functional (and most have been functional for several hours). We are awaiting an update as to what caused the issue with the traffic routing, as the change made by the vendor should not have impacted anything outside of internal addition/removal of phone numbers. We will update when we have more information on root cause, and prevention of recurrence.
Nov 18, 12:55 EST
Vendor made a change, which was manually tested by our team before hand and deemed safe and insignificant. The change was pushed out for a set of us numbers and that batch failed for some unknown reason. We asked the vendor to roll back immediately. The rollback is almost complete. This issue only impacted US domestic inbound numbers.
Nov 18, 07:03 EST