During the recent Leagues Cup quarter-final between Los Angeles and Monterrey, the referee and fourth official communicated with VAR using a traditional landline phone.
Said Martinez (HON) awarded a penalty kick to Los Angeles after only 18 seconds played in the match, without any VAR intervention. However, in the second half, VAR Ismael Cornejo (SLV) wanted to invite the referee to an on-field review for a possible penalty kick. Due to technical issues with the HawkEye system at the venue, the video assistant referee had to call fourth official Raul Castro (HON) using a landline phone. Following the review, referee Martinez awarded a penalty kick to Monterrey, who eventually won 3-2 and advanced to the semi-finals.
Source: Leagues Cup