There is a free edition of the HAfs product gflow mentioned above. (
From this website) I use the free edition for my home freeswitch and also development PBX cluster. I found out about it from an ITSP I worked with...so as gflow said its rock solid. (Meant for ITSP/carriers/mission critical stuff). And of course I consider my home phone to be mission critical in case I'm ordering pizza.
I think this product is very different from the approach Mark takes. I think Mark's approach involves creating redundant and shared components to gain HA. The HAfs approachs requires no shared components; i.e. one standalone box just takes over for the other standalone box. I love the simplicity.
So if this is for home use I suggest you download the free edition. There's an included user manual and installation guide in the HAfs download package. And, although their website says they don't offer support for the
free edition, if you email them they'll probably send you an answer. They actually helped me a lot to get started.
The only caveat is, if you have $0 budget and you need to build something at scale, then you may have to take Mark's approach (all open source). It's also nice to support the people who put their time into FreeSWITCH. And if HAfs free edition meets your needs, send Mark a coffee anyways!