Inband

Inband, typically written as in-band, is an adjective used to describe information that is carried within the same channel, frequency band, or data stream as the primary payload. The concept is used across telecommunications, networking, and signal processing to distinguish embedded control or signaling from data transmitted over a separate channel, often called out-of-band signaling.

In telecommunications, in-band signaling historically embedded control signals within the same audio path as voice. This made signaling susceptible to interference, eavesdropping, and misinterpretation, and led to the adoption of out-of-band signaling such as SS7 in traditional networks. Examples include tone-based signaling in older telephone systems and, in some cases, DTMF tones used for dialing or menu navigation, which travel in-band with the speech signal.

In computer networks and device management, in-band management refers to management traffic that traverses the same network as user data. Out-of-band management uses a separate network, interface, or channel, providing continued access for configuration and recovery even if the primary network plane is down. Many devices offer both options, with out-of-band management often deployed for security and resilience.

In signal processing and multimedia, in-band can also describe data embedded within a stream, such as control information carried alongside the main payload in a protocol or codec. The in-band/out-of-band distinction informs system design, security considerations, and fault tolerance across industries.