Definition - What does Narrowband mean?
Narrowband refers to data communication and telecommunications tools, technologies and services that utilize a narrower set or band of frequencies in the communication channel. These utilize the channel frequency that is considered flat or which will use a lesser number of frequency sets.
Techopedia explains Narrowband
Narrowband is typically implemented in telecommunication technologies to carry voice data on a limited number of frequency sets. The size of the message sent via a narrowband technique utilizes lesser bandwidth than the cumulative bandwidth of the underlying channel.
Narrowband is also used in sending audio spectrums that consume a restricted range of frequencies. The US FCC has allocated a specific range of frequency for mobile radio services based on narrowband that spans from 50cps to 64kbps.