Office + Stationery

Hello Together We are an office with 8 employees. Our problem: We are often on the road and it is difficult for the secretariat to give information whether someone is available or not. (The appointments are usually short term and have an unpredictable duration, therefore Outlook entries make little sense). We are looking for a system that shows the secretary who is in the office and who is not (to forward calls etc.) Our telephone system cannot do this (and it is too new to replace it). Does anyone know of a radio-based attendance system? I can't find anything. Thanks Matt