A newer open radio protocol for Winlink users, and for amateurs everywhere is available already. ARDOP (Amateur Radio Digital Open Protocol) is a new (from 2018) cooperative radio protocol project in which the Amateur Radio Safety Foundation and Rick Muething, KN6KB, of the Winlink Development Team are proud to have a major role. ARDOP will ultimately replace WINMOR in the Winlink system because of its superior features and multiple platform (OS) support.
The protocol design is open, and the software implementations will be open-sourced. This means you can expect the protocol to take different forms, like a virtual TNC using sound-card software on Windows, Linux, Apple OS X, iOS, and Android, or in hardware, like a USB plug-in or 'add-on box' using today's low-cost DSP CPU chips.
This is an important step as one of the most efficient protocols has been the proprietary Pactor 2 and above, but modems cost easily $1,000 plus and each user must have a modem to use it (Pactor 1 modems are cheaper but are incredibly slow). VARA is a cheaper alternative but still costs money and is not as efficient. Open source also means a better chance that it will be fully cross-platform.
A big plus with ARDOP is that it will work with just sound cards, or with radios such as the Yaesu FT-991A with a built-in sound card and similar radios, just a USB driver.
From what I see in Winlink Express the protocol is already listed for use but it does require that the Radio Message Server (or P2P station) that you are connecting to, supports the protocol.
Amateur Radio Digital Open Protocol The ARDOP project is a joint development effort among amateur radio developers that seeks to provide a specification and implementation (software or hardware) for a modern versatile open digital protocol. Target Objectives