didn't know if you had taken a look at HIPAA services such as:
If they have an API, you might be able to leverage that.
eFax (listed in your link) is one of the options I was considering. Their API is primarily secure HTTP Post, which FM can do. I guess I would love to know if someone is already levering one of these solutions with success. I don't necessarily want to re-invent the wheel if I don't have to.