A telephone entry system traditionally has a telephone line attached to it and it then calls a landline or cell phone number programmed into it when a visitor presses the button on it. These days with landlines being phased out, telephone entry systems use cell phone technology to replace the landline. That also eliminates the need for running a wire to the intercom. It can still call landlines or cell phones.
Copyright IntercomsOnline.com. All Rights Reserved.