In general, the subject matter described in this disclosure can be embodied in methods, devices, and program products for selecting a wireless transmission mechanism. A computing device receives a request to begin a full-duplex voice communication session with a remote computing system. The computing device identifies that it has wirelessly connected to both a WWAN access point and a WLAN access point. The computing device determines whether a level of non-voice session data that is queued for transmission or receipt by the computing device falls beneath a threshold level of data, and as a result, switches to using a single one of multiple WLAN radio chains. The computing device communicates data over the single one of the multiple WLAN radio chains, including voice session data from the full-duplex voice communication session.