The disclosure pertains to a communication system for effecting a voice or video call between at least a source user speaking a source language and a target user speaking a target language. A translation procedure is performed on call audio of the call to generate an audio translation of the source user's speech in the target language for outputting to the target user. A notification is outputted to the target user to notify the target user of a change in the behavior of the translation procedure, the change relating to the generation of the translation.