The Ameritec AM2 NiagaraTone units are self-contained, portable units featuring a built-in user interface, but also allow the user to develop a test environment with the ability to test highly complex call scenarios, under the control of FeatureCallTone, Ameritec's WindowsTone based graphical user interface. Used alone it can simulate one to hundreds of telephony subscribers, and when grouped in a system, consisting of any Ameritec Niagara, CrescendoTone or SquirtTone, thousands of telephony subscribers can be simulated. The Niagara Family has the flexibility to suit development, production, quality assurance or regression test needs.