You are probably inadvertantly did a busy station signal to sta 24 and are still queued up to it. Call 24 AND have them ANSWER to clear it. You may have to do it multiple time as most systems will allow 8 stations in the queue
I'm have trouble seeing through the internet and do not know what make or model you are referring to?
Have you tried being ON THE HANDSET and then pressing the handsfree/speakerphone key?