You have several choices. One is to plug a wireless phone base station into Ooma. Then you can have as many extensions as you have wireless handsets.

If you want all the Ooma features at each phone, you need an Ooma "Scout" for each extension. This allows you to easily see voice mail waiting alert and play your recorded voice mail at each extension. I have a scout in my kitchen for convenience.

http://ca.ooma.com/products/ooma-scout/features

Regarding a home fax machine, I was never able to get faxing to work reliably with Ooma. I decided fax was basically an obsolete technology and tossed my machine. There are ways to fax with your PC and to receive documents as attachments to email that give you 90% of what a fax machine would.

Here's what Ooma says about fax:

http://www.ooma.com/app/support/faxing-ooma

My experience goes back to 2009 and maybe things have changed, but I'd say don't bother with fax anymore. Nobody in the chipping hobby but Doug Saito uses fax anyway .