A mobile communications device having an LTE radio technology and at least one other technology (for example, Bluetooth or Wi-Fi) determines whether transmissions using the other radio technology causes, or is likely to cause interference in reception of LTE signals. If such interference exists or is likely, then a signal indicating interference is sent to the LTE base station, which can take action to try to mitigate or prevent such interference. The mobile communications device can have a timer so that the interference indicating signal is only sent periodically, either at regular intervals, or whenever the interference is determined to exist after the timer period has expired. In some cases, a signal indicating that the interference level has reduced can be sent, again either at regular intervals, to whenever the interference level changes.