Sam Smith nearly missed Band Aid call

British pop star Sam Smith nearly missed Bob Geldof's invitation to join Band Aid 30 because he refuses to answer his phone to private numbers.

The Stay With Me singer asked a member of his band to pick up the mysterious call and was shocked to discover the Live Aid founder was on the line.

Despite the initial confusion, Smith accepted the offer to sing on Do They Know It's Christmas? for Geldof's latest charity project to help fundraising efforts for Ebola sufferers in West Africa.

Smith tells U.K. chat show host Alan Carr, "I don't pick up to unknown numbers so when Geldof rang I had no idea it was him. When he called I gave my phone to a band member and then he realized Bob was on the other end and gave it back to me. He's a lovely guy. It's a legendary thing to do but I was glad to help. I thought there would be an ego fight but Bono was amazing and Chris Martin was great to meet."

The interview on Alan Carr: Chatty Man airs in the U.K. on Friday (21Nov14).