MOH Definition

Modem-on-hold (MOH) is a feature of V.92 modems that allows users with dial-up connections to switch to an incoming voice call when a call waiting signal is detected while connected to the Internet, and then resume using the Internet after the voice call is terminated without requiring redialing and a new handshake (i.e., negotiation between the modems at both ends).

MOH likewise allows the user to initiate a voice phone call while connected to the Internet. In this case, the MOH program suspends the data connection between the modem and a dial tone appears on the telephone handset. When the call is complete, the modem returns to the Internet connection.

MOH provides a hold time in which the user must end the voice call in order to prevent the Internet connection from being dropped. The length of this time is set by the Internet service provider (ISP) anywhere from 10 seconds to infinite. The MOH application typically can display on the user's screen both the allotted hold time and a countdown showing how much time is left for the phone conversation.

For MOH functionality, the user must have call waiting service provided by the telephone service provider. In order to additionally have caller ID (identification) function while on the Internet, the user must also subscribe to caller ID on call waiting service from the telephone company, not just ordinary caller ID.

If the user's modem is V.92 but the ISP only supports V.90, in the event of an incoming call, MOH will drop the Internet connection and answer the voice call. Prior to V.92, a call waiting signal arriving while the user was on line often caused the Internet connection to be dropped without establishing a voice connection.

Created November 10, 2005.
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