A caller identification (ID) modem is any modem that connects to a phone line and supports caller ID functionality, often with the caller ID built into the modem. When someone calls, a caller ID modem will show the name and number on the computer screen, so users know who is calling without looking at the phone itself and without calls interrupting the Internet connection. Some caller ID modem units can send call information to email or via short message service (SMS). If users do not wish to answer the call, then this modem can typically record a message, which can be played back through the computer. Having a caller ID in a modem is uncommon so, unless a modem specifically markets this feature, it is unlikely that a common modem will have caller ID.
People who use a modem to go online have one major problem: phone calls. If someone tries to call, it will interrupt the Internet connection, which can ruin lengthy downloads and can be an annoyance. With a caller ID modem, whenever someone calls, his or her information will be displayed onscreen. This enables users to screen calls and to only answer if calls are truly important.
If users do not wish to pick up the phone immediately, are not at the computer or are out of the house, then a caller ID modem can send call information to users. The most common way of doing this is via email, but the information also can be sent via SMS. This makes it easier for users to remember who recently called and enables users to immediately respond to important calls.
Another caller ID modem feature is to act as an answering machine. If the user does not want to pick up the phone or is not around to get it, then a message will be recorded through the modem, rather than through a separate answering machine. This message can be played back through the computer, because the voicemail is saved as a simple audio file.
There are many common features associated with modems, but having caller ID is not one of them. This means most modem units will not be a caller ID modem. If the modem does not specifically say it has caller ID functionality, then it is doubtful that it can collect call information or record voicemail messages.