Beginning in the early 2000s, Exchange ActiveSync (EAS) began to be available for licensing. At the time it was a client only protocol license. Motorola was the first licensee and began with a license of the 2.1 version of EAS.
Various other organizations licensed EAS over time and Microsoft eventually started
licensing the server side of EAS in 2007. The protocol licensing continued until 2008.
Exchange ActiveSync began being licensed in the early 2000s to mobile device manufactures. The current list of licensees is located on the
Microsoft Intellectual Property licensing page.
Exchange ActiveSync (EAS) has iterated though several versions (from 1.0 to 14.1). Because EAS is licensed as a series of patents (and not given as computer code to other companies), different clients and servers implement a subset of the entire
features of the protocol and the implementations are written by each company that has obtained a license. A
compatibility list has been posted online that helps those interested see which features are implemented in which phones.
Desktop ActiveSync (Windows 95, 98, XP, 2000) was a desktop application designed to synchronize and set up Windows Mobile devices though a connection
(USB, Wi-Fi, Bluetooth, IR) to a computer. This varies greatly from Exchange ActiveSync which is a wireless synchronization protocol. The desktop application is capable of syncing with Outlook on the desktop but not syncing wirelessly
from the device to the email server (though it can configure these settings). Since the names were so similar, ActiveSync (the desktop application) has changed its name to Windows Mobile Device Center (WMDC).