The receiver can be carried from room to room. The transmitter is always battery operated and is screwed into the door frame. It is waterproof and contains the doorbell switch. These systems have security codes which means that if your neighbour has a similar system, you can easily change the code so that your neighbour's system does not interfere with yours. You can get two types of wireless doorbell - one you can hear or one you can see.
Some systems also have a vibrating alert.
You will also find that some multi-functional wireless systems include a doorbell alert. You will find more details about these systems in our factsheet Devices to alert you to different sounds around your home. These systems can make all the lights in your house flash or dim whenever the doorbell rings. They are particularly useful if you need to know your doorbell is ringing wherever you are in the house. These systems depend on how your home is wired, for example, if you have two lighting circuits, one for upstairs and one for downstairs, you connect the system to one circuit and therefore light up only one floor.