An example embodiment may involve determining a quality of service level for network traffic associated with a WCD. The WCD may be served by an air interface of a RAN. The air interface may include a primary signaling channel and a secondary signaling channel, where the primary signaling channel simultaneously spans all of a plurality of contiguous subcarrier frequencies and the secondary signaling channel does not simultaneously span all of the plurality of contiguous subcarrier frequencies. The example embodiment may further involve, possibly based on the quality of service level for the network traffic associated with the WCD, selecting the primary signaling channel or the secondary signaling channel for transmission of a signaling message to the WCD. The example embodiment may also involve transmitting the signaling message to the WCD via the selected signaling channel.