Many businesses use a business telephone service that allows several customers to call in at once without receiving a busy signal. A multi-line caller ID identifies the name and number of each caller on each of these phone lines. These systems can either be purchased as software, which shows the name and number of the callers on a computer screen, enabled by the software, or as hardware, operated as a stand-alone device. Multi-line identification software and hardware programs also have other features, such as identification of the callers by color, identification of which calls are incoming and which are on hold, and indication of the length of each call.
Software for a multi-line caller ID is connected to the main phone line and can be installed on any computer. The names and phone numbers of each caller appear on the screen, in chronological order. Having the ability to quickly view multiple callers makes it easier to manage incoming calls and to avoid missed calls.
This type of software often has additional features which further improve organization. For example, the software may sort the names and numbers of incoming caller and use alternating colors on the screen, making it easier to read through the list of calls. Advanced software can assign a small icon or different colors to the different types of calls, such as "incoming," "answered and on hold," or "currently on call with a private line." The software can also track the length of time a call stays on hold, giving the person managing the calls an easy way to prioritize answering each call.
Multi-line caller ID hardware is a either a stand-alone device that works with the telephone or a device that is built-in to the telephone itself. The hardware has a small screen that lists the caller's name and phone number and generally shows calls in the order in which they were received. Most multi-line caller ID hardware systems have general features, such as allowing a call to be placed on hold, transferred to another office or phone line, and answered by pressing a button or tapping on a touchscreen located on the hardware itself. Unlike multi-line caller ID software that works through any computer, the hardware units must be installed in each office that needs to use the caller ID.