Greentree Applied Systems was incorporated in 1982 as a custom software, consulting, and hardware installation company by Don and Nora Putnam. Greentree designed systems and software for local, state, and national businesses that included equine management, medical billing, church and association membership, and accounting. The company experienced significant growth during the early ’80s due to the introduction of desktop computers into the workplace, which created an immediate need for custom software and hardware design.
In 1990 the focus of the company became Utility Billing as Greentree partnered with utility companies across the country, as well as meter manufacturers worldwide. The partnership resulted in a complete utility management software, UMS-Win, that was compatible with the new technology of Microsoft Windows.
In 2001, Greentree was acquired by Master Meter and operated as Master Meter Systems while operating under the leadership of the Putnams.
In 2015 the Putnams re-acquired the utility billing business from Master Meter and Ampstun was born. The existing product was expanded upon and now offers a comprehensive suite of Utility Management Software in the cloud.