Details from their web site ~
“A Festival of Nine Lessons and Carols is broadcast live on BBC Radio 4 on 24 December at 3pm (10:00 EST or 07:00 PST). The service is also broadcast at 2pm on Radio 3 on Christmas Day, and at various times on the BBC World Service.
“In the United States the service is broadcast by around 300 radio stations, including American Public Media and its affiliates (Minnesota Public Radio and WNYC-New York, for example). Unfortunately there is no list of radio stations that are broadcasting the service, so it’s best to contact your local stations or check their online listings.”