Hi. It will always depend on the distance , but it is a useless discussion, today the doormen should be wired with a network cable, since most likely (in new works) that before finishing the work the owners change of idea and want a "goalkeeper viewer". If the section is short, or your expectations are not to modify in the future, you can use thin cables of two telephone pairs (doorman). Of course, all this is based on a job where quality prevails over a monetary issue, whether for own or third parties. It is my professional opinion. regards