Methods and devices for connecting an accessory device to a connector port of a mobile communication device and automatically detecting an operational mode of the connector port are provided. The method includes implementing a USB Type-C device detection at an electronic processor of the mobile communication device and monitoring a first and second pin of the connector port for pull-up and pull-down signals from a connected accessory. The method also includes interrupting the USB Type-C device detection when a pull-down signal is detected and determining whether an accessory signal is detected at a third pin of the connector port. The method also includes implementing a LMR accessory detection when the accessory signal is detected and completing the USB Type-C device detection when the accessory signal is not detected.