The initial version of WinFax only worked on fax modems containing a specific chipset, and was only capable of sending faxes; it could not receive them. This was remedied with the launch of the WinFax PRO 2.0 product during the summer of 1991. One of the key factors that differentiated this version of WinFax from other fax software packages of the time was the deliberate attempt to make the program compatible with all fax/modems. Prior to the introduction of WinFax PRO 2.0, competitors concentrated primarily on building software that would only work with a single brand of fax/modem hardware. At the same time that it launched its WinFax PRO 2.0 product, Delrina also announced an OEM version of the same product designed to be bundled with new fax/modems. Within a few months, eight modem manufacturers had agreed to bundle this OEM version (called "WinFax LITE") of the program along with their own product. By the summer of the following year this number had grown to 50 OEM partnerships with various fax-modem and computer system manufacturers to bundle the "LITE" version of Delrina's WinFax software with their own products. By February 1993 this number had grown to over 100 OEM partnerships.