Communication channel
A communication channel, also abbreviated as com channel or comm channel, was a medium used to communicate a transmission of information from a transmitter to a receiver via a communications frequency. 

According to Starfleet guidelines for away team members during a "medical emergency on alien terrain, it is recommended [to] keep an open comm channel at all times." () 

During his brief time aboard Deep Space 9, in 2373, Cardassian exile Tekeny Ghemor was given  26 hour-a-day computer access, and a his own private subspace comm channel. ()

Specified channels 
 Central channel, a communications channel used on Eminiar VII
 Channel 90, a net channel
 Channel 178, a net channel
 Channel E
 D channel, a communications channel used by Starfleet
 Emergency channel, a communications channel used by Starfleet
 Emergency Channel D, a communications channel used by Starfleet
 Emergency medical holographic channel, used to communicate with an EMH
 Subspace channel

External link 
 

Communications technology