Intermittent voice quality issues with phone calls to or from Telstra Mobile Phones operating in FNQ. Issue commenced 20th August and ongoing. Examples: intermittent silence for 1-3 seconds during conversation, call drop-outs, silence on answering, one party cannot hear the other party. Possible cause: Someone operating an illegal mobile phone booster in the Cairns/Tablelands region, e.g. Courier vehicle.