A communications system may include at least one mobile wireless communications device, and a wireless communications network for sending text messages thereto. More particularly, the at least one mobile wireless communications device may include a wireless transceiver and a controller for cooperating therewith for receiving text messages from the wireless communications network. It may further include a headset output connected to the controller. The controller may be for switching between a normal message mode and an audio message mode based upon a connection between the headset output and a headset. Moreover, when in the audio message mode, the controller may output at least one audio message including speech generated from at least one of the received text messages via the headset output.