Although Duff only called time on his 100-cap career just over two weeks ago, Trapattoni and his assistant Marco Tardelli both said last week that they were hopeful of seeing the winger pull on a green shirt again.
Trapattoni hopes to speak to Duff on Tuesday night after the Republic's friendly against Oman at Craven Cottage.
Kevin Doyle (who will skipper the side against the Gulf state): "I think from what I have heard Duffers is well and truly in the retired camp.
"I think he wants to be left alone for a while."