Every day we see the important role technology plays in keeping us connected, and we know that our customers at T-Mobile rely on our network because they know we work to ensure connections to family, loved ones and service providers. This is a responsibility that my team takes very seriously and it is our highest priority. Last Monday, we didn't meet our standards of excellence.

Many of our customers experienced problems with their voice and text service, specifically with calls. My team took immediate action: hundreds of our engineers worked tirelessly alongside suppliers and partners around the clock to resolve the situation as soon as it was identified. Data connections continued to work, as did non-VoLTE calls; and services such as FaceTime, iMessage, Google Meet, Google Duo, Zoom, Skype, allowed our customers to stay in touch. In addition, many customers were able to use voice-over-circuit connections. On the other hand, Sprint customers were not affected. VoLTE and text, in all regions, were fully recovered by 10pm PST (Monday night). I am pleased to say that the network is fully operational and we are and will continue to work every day to keep it that way.

Our engineers worked throughout the night to find the cause of what happened last Monday, to prevent it from happening again. It is known that the event that caused it was a circuit failure of a fiber leased from a third-party provider in the southeastern United States. This is something that happens in all mobile networks, so we have worked with our suppliers to build redundancy and resiliency to ensure that these types of circuit failures do not affect our customers again. This redundancy failed us, and resulted in an overload situation that was then aggravated by other factors. This overload resulted in IP traffic spilling over from the southeast to create significant capacity issues across the IMS (IP Multimedia Subsystem) core network that enables VoLTE calls.

We have worked with our IMS (IP Multimedia Subsystem), as well as IP providers, to add additional permanent protections to prevent such an event from happening again. We are still working to determine the cause of the initial overload failure.
Therefore, I want to personally apologize for any inconvenience that occurred this past Monday and thank you for your patience as we work through the situation toward resolution.

Neville Ray
T-Mobile President of Technology