mine is 1970s build and has underground phone cable, they would more than likely just "mole" it, ala what the gas installers do - basically dig a narrow short trench at each end and then the "mole" (hydraulic ram IIRC) pushes its way through to the other end
Only thing is my phone line comes in from the road, and the back of my house faces the road, there's also the matter of poured bitumen sealed foundations (even some of the cables and pipework is buried in the stuff)
Biting the hand that feeds IT
