What term is used for frequencies designated for voice and/or data transmission?

The term that refers to frequencies designated for voice and/or data transmission is "channel." In telecommunications and broadcasting, a channel serves as a pathway for the transmission of information over a medium, which can include sound, data, or other forms of communication. Each channel is associated with a specific frequency range, allowing different channels to operate simultaneously without interference.

For instance, in radio communications, multiple channels can exist in a defined bandwidth, enabling various conversations or data transmissions to occur concurrently. This is a critical aspect of managing radio frequencies effectively, as it ensures organized and clear communication across different users.

The other options represent related concepts but do not directly answer the question. "Bandwidth" refers to the range of frequencies within a given band that is used for transmitting signals, while "signal" refers to the actual information being transmitted. "Frequency Modulation" is a method of encoding information in a carrier wave by varying its frequency. Thus, "channel" is the most precise term for the designated frequencies used for voice and data transmission.