If you can put his litterbox and/or a worn but unwashed t shirt or pair of smelly shoes of yours out on the deck this may help lead him home
Go around the neighbourhood at dusk/dawn calling him, rattling a treat container or tap a spoon on his dish or tin of food. Bring a flashlight to pick up the shine off his eyes from under cars/decks/bushes or up trees.
If you can poster the neighbourhood, plus leave one w/ local businesses, grocery stores, vets & all animal shelters in the area that will help garner attention that this boy has a home who wants him back
Contact the vet clinic/shelter that originally tattooed him & ask them to update the file to include the current phone # & address, that way if the collar becomes lost & someone traces the tattoo they will have the correct info.