Large construction activities like metro works, bridges, flyovers, campuses, dams etc are spread over large areas. Working conditions are normally outdoors and often hazardous. Activities are normally within city limits but the environment is not conductive for use of mobile phones or landline phones, in spite of network being available. Communication between workers and supervisors and engineers is always ongoing. It is neither convenient nor affordable to dial numbers. Passing message on time is very critical, often a same message is required for a group of workers, whether working on ground or on cranes etc. Radios are rugged for such environments and message is passed by just pressing the PTT button and communication.