Actor Robert Wagner, his wife, Jill St. John, and comic Joe Piscopo were the first Frank Sinatra fans to leave birthday messages on a pay telephone line set up for Ol' Blue Eyes as he turns 75.

Piscopo, who imitates Sinatra in his comedy routine, and the other celebrities kicked off the birthday hotline Monday.For a maximum $4 charge, callers who dial 1 (900) 420-2448 can record messages for Sinatra, who turns 75 Wednesday. Profits go to charity.

The hotline will remain open through October 1991, then the messages will be given to Sinatra, said Esther Perman, a spokeswoman for Chivas Regal, the sponsor of Sinatra's Diamond Jubilee world tour. The tour began Tuesday in New Jersey.