HylaFAX+ is described as 'enterprise-class open-source system for sending and receiving facsimiles as well as for sending alpha-numeric pages. It collaborative fork of HylaFAX at hylafax.org'. There are four alternatives to HylaFAX+ for Windows, Mac, Self-Hosted solutions, FileMaker and Linux. The best alternative is ActFax. It's not free, so if you're looking for a free alternative, you could try HylaFAX. Other great apps like HylaFAX+ are 4-Sight FAX (Paid) and Snappy Fax (Paid).
Introducing a business-strength, Internet-enabled fax solution providing the communications power and portability you need to achieve profitability in today’s fast-paced, increasingly mobile, cost-conscious economy.