Moved a norstar 3x8 dr5 last week for a customer to a new building. All phones are t7316. In the warehouse area there is one office with one phone. Outside this office is a storage area and a loadout bay. They would like some kind of speaker or horn in both of these areas that woud go off when that phone rings or when someone pages that extension so that it can be heard outside the office. What are some options for this?