From Vatican Insider:

“I had my cordless phone with me, this call arrives so I pass the phone to Pope Benedict and I hear him say, “Holiness, I promise from now on my total obedience and my prayer”. These are moments I cannot forget…”. These were Pope emeritus’ first words to his successor Francis on the evening of his election. He pronounced them right after dinner, using a cordless phone. Ratzinger was able to repeat to the newly elected Bishop of Rome, the words he had spoken at his last meeting with the cardinals before leaving the Apostolic See, when, without knowing who would his successor be, he had told them, “Among you there is also the future Pope to whom I promise my unconditional reverence and obedience”.