- T-Mobile rolled out an Automated Ball-Strike Challenge System using private 5G
- The carrier deployed the system in all 29 MLB stadiums in the U.S.
- T-Mobile is using Ericsson private network gear
T-Mobile is bringing private 5G sophistication to the people’s game with the first-time deployment of an Automated Ball-Strike (ABS) Challenge System that lets players dispute calls by home-plate umpires.
On opening night this week, Major League Baseball will fully launch its ABS system. If a player thinks an umpire missed a call, they can tap their helmet to request a review. Within seconds, the ABS confirms or revokes the call with a graphic shown on the scoreboard and in the broadcast.
“T-Mobile has been working with MLB to implement an automated ball strike monitoring system for several years,” said Daryl Schoolar, analyst at Recon Analytics. “It was used during 2025 major league spring training and regular season minor league games.”
“The ABS system does not replace umpires. Instead, it is used when a team wants to challenge how an umpire ruled on a pitch. Each team has two challenges per game. The big news is this season MLB and T-Mobile are bringing the system to the big leagues,” the analyst said.
Clearly, this has required a lot of work behind the scenes to operate seamlessly. “ABS uses 12 high-speed and high-precision Hawk-Eye cameras positioned around the field, capturing each pitch to instantly map and triangulate its exact location,” Scott Jacka, T-Mobile senior director of technology development strategy, told Fierce.
“Once the pitch is thrown, T-Mobile’s 5G private network transmits pitch data from the ABS system via 5G-connected devices — providing quick and secure pitch location verification,” Jacka said. He added that ABS requires fast, reliable and secure data transmission during live games, and a 5G private network provides a low-latency, on-site connection that allows pitch data to move quickly and directly between devices and MLB systems in real time.
The system is dedicated to the ABS calls and will not handle other in-stadium systems like point-of-sale (POS) operations. The system delivered as part of T-Mobile's Advanced Network Solutions portfolio is “essentially a hybrid public-private 5G setup at each MLB ballpark where on-premise RAN nodes connect 12 cameras for the ABS challenge system,” Asad Khan, SNS Telecom & IT’s 5G research director, said.
“Several other use cases are also supported both by the on-premise private networks and T-Mobile's public cellular coverage (which is enhanced by DAS [a Distributed Antenna System] within the ballparks), including remote production, data transfer for photojournalism, a biometric ticketless entry system and public safety communications,” Khan noted.
Rapid deployment
T-Mobile deployed the private 5G ABS system over 18 months in all 29 U.S. MLB stadiums. “Thanks to our partnership with MLB, we were able to get the installation and deployment down to a matter of days for each ballpark,” said T-Mobile’s Jacka.
T-Mobile is using its mid-band 2.5 GHz spectrum for this system, Recon’s Schoolar said. And the in-stadium 5G private networks are built using Ericsson Private 5G and Dot radios on n41 2.5 GHz midband, T-Mobile’s Jacka noted.