T-Mobile now has a partial answer that pertains to its extensive nationwide outage Monday. T-Mobile is now able to deliver calls and text messages for most of an entire day.

A fiber-optic circuit failed, and its backup circuit also failed. It caused a chain reaction that strained the network. Many calls and texts could n’t make it through.

T-Mobile customers rely on our network to ensure they have connections with family, loved ones and service providers. This is a responsibility my team takes very seriously and is our highest priority priority.

The trigger event is known to be a leased fiber circuit failure from a third party provider in the Southeast. This is something that happens on every mobile network, so we’ve worked with our vendors to build redundancy and resiliency. This overload resulted in an IP traffic storm that spread from the southeast to create significant capacity issues across the IMs (IP multimedia subsystem) core network.

We have worked with our IMs (IP multimedia subsystem) and IP vendors to add permanent additional safeguards. We’re continuing to work on determining the cause of the initial overload failure failure.

I want to personally apologize for any inconvenience that we created yesterday. Thank you for your patience as we worked through the situation toward resolution.