It is unfortunately a rather common situation in RSI. if it is your boothmate, the quickest way would be to make sure that your microphone is muted in the main RSA event, and then speak to your boothmate in InterStar ICP and asked to switch to the correct channel.
Alternatively you can send a quick “wrong channel” message to your boothmate or if it is a different booth, to the entire interpretation team to check their outgoing channel.