That means you don't have to run power or any other wires to the units at the front door or on your desk. Some systems even let you add a remote door lock control, which is nice if you want a delivery person to just slide a package in the front door. Many digital systems also provide quieter operation so you won't have any static noise drowning out your conversation. That's where a wireless intercom system you can quickly run off sales people with barely a break in your concentration. You also want a system that provides digital security so neighbors with similar units or cordless phones can't listen to your conversations. One solution to this problem is to add an intercom system with a door phone to your residence... Once you get rid of the distraction and head back to your office, now you have to get back in the mode of concentration you were previously in. Then you have to decide whether to put the call on hold and make the journey to the front door for what could very well just be the