Major League Baseball has installed a video setup and secure telephone links in all 30 stadiums in preparation for Thursday's debut of instant replay.

"A television monitor and a secure telephone link to MLB.com [offices in Manhattan], placed next to the monitor, have been installed during the past few weeks at every Major League ballpark," a story on baseball's official Web site says.

The video and telephone linkups vary by location, with some in the players' dugouts and others in the umpires' locker rooms. Every game will be "monitored and staffed by an expert technician" in addition to an umpire supervisor or former umpire at MLB.com headquarters.

Instant replay will be used after disputed home run calls, but not for balls and strikes or safe/out calls. While replay could affect the outcomes of some games, operating the required technology shouldn't be that complicated.

The professional football, hockey and basketball leagues in North America have been using instant replay for years, and even Major League Baseball already records every game and streams them live over the Internet. All broadcast feeds will be used to give replay officials a number of different video angles, helping them determine whether fly balls cleared the outfield fence, or whether a fly ball that leaves the playing field was fair or foul.