The service will be rolled out across the the tunnels, starting this week in tunnels between Westlake Station and UW, which includes Capitol Hill Station and University of Washington Station. Service between the International District/Chinatown Station and Downtown will open later this year while service will begin in the Beacon Hill tunnel in 2017.
The Northgate light rail extension, which is scheduled to open in 2021, will be service-ready as well.
For now, service will also only be available to T-Mobile customers. Verizon and AT&T customers will start getting service next month. Sprint customers are scheduled to get service at a later date.