House phone Alarm system

New build is nearly ready but house alrm has not been installed. Electrician says it's too late to install wired system. Is this correct?? Should I insist it's done now before work is finished.....or are the battery operated systems ok? Can anyone recommend one???....Thanks.

it is still possible to put in a wired system, but the wires would not be hidden. Over time though, with painting the walls, they become hidden.

phonewatch do a wireless system, entire house done in a few hours