In 1999, Young-sook says she is 28 and was born in 1972. This is due to the unique age-calculating-system used in Korea. When a Korean baby is born, they already one years old.
This film is based on the 2011 British/Puerto Rican film The Caller (2011), starring Rachelle Lefevre and Stephen Moyer.
"The Call" is a horror variation on the South Korean film "Il Mare", a drama/fantasy/romance which was remade as "The Lake House." All three use the technique of individuals communicating across two different time periods. "The Call" uses a cordless landline phone while the other two use a mailbox.