TekFax
TekFax is a SIP (Session Initiation Protocol) fax receiver server (Based on RFC 3261) for Windows (Windows Vista, 7/8/10/11, 2008-2022 Server).
Features
- Simple, easy to use interface.
 - UDP, TCP and TLS transports for SIP signalling.
 - TekFax can forward incoming faxes to configured recipients via e-mail in TIFF format.
 - Supports UPnP for NAT traversal. You can also set external IP address manually.
 - Quick and easy installation.
 - Runs as a Windows service.