What is Push to Talk feature in mobiles in instant communications system?

Push To Talk (PTT) is a business radio service that uses mobile phones i.e.Nokia Mobiles instead of walkie-talkies.

It allows instant communication either on a one-to-one or one-to-many basis. A fully managed Push To Talk (PTT) service allows your field workers to keep in constant contact with the office as well as each other. By using existing mobile phones instead of dedicated walkie-talkie radios, Push To Talk (PTT) also allows you to better manage equipment costs as staff need only carry one device.