A cell phone speakerphone is a device which allows someone to use a cell phone without holding the handset to the face to speak and listen. There are a number of reasons why someone might be inclined to use a cell phone speakerphone, ranging from the need to comply with hands-free laws regulating cell phone use while driving to the desire to hold a conference call with the assistance of cell phones. Many electronics stores sell speakerphone units for cell phones and people can also order them through manufacturers.
A wired speakerphone connects to a jack on the cell phone. When the phone is plugged into the speakerphone, audio will be routed through the speakerphone. The loudspeaker enables projection of sound from the incoming call, and a microphone in the base picks up sound from the room so that it can be routed to the other caller or callers. Wireless cell phone speakers use systems like Bluetooth to communicate with the speakerphone base unit, rather than requiring the phone to be physically connected. In either cases, the cell phone speakerphone usually needs to be calibrated before a call to make sure that the volume levels are comfortable and to check for feedback.
With a half duplex cell phone speakerphone model, only one person can talk at a time. While someone is talking, sounds from the other end of the connection cannot come through. Thus, there is a bit of a lag between the people talking, as the connection must be quiet in order to switch over to the other person. A full duplex speakerphone allows sound from both directions at once, for a more natural conversation. Full duplex technology is more expensive.
A common reason to use a cell phone speakerphone is in the car. A car speakerphone can allow someone to operate a phone with voice commands and to conduct calls without touching the phone. This technology is used by people who need to place calls in the car or who want this option. In some regions, people are required to use hands-free devices with cell phones in the car due to safety concerns.
Another reason is for conference calling. Using a cell phone speakerphone several people in a room can participate in a conversation together and can conference with callers in other locations. This allows everyone in the room to hear and respond at once, and is more comfortable than having people hold phones up to their ears to listen. Speakerphones are also sometimes used by people in their offices for hands-free cell phone use.