I have switched to 2 talk and cut off the phone lines - we have warp-speed telstra cable and I am very brave as my wife and I rely heavily on the phone for our businesses -

I have opted to use after trying several devices, a Linksys SPA-2102 and have set it up to the instructions set out by 2talk  - 

the phone is OK reliable with good sound quality but I have had some problems with Keying in numbers and I don't here a beep when someone is trying to get through on the other line.

The people at 2talk have a policy it seems they only answer the phone if they can answer it in a few rings unlike Slingshot who put you on hold for 1 to 2 hours ever time you call. 

They Have a forum for "solving problems" it got filled up with a boat load of complainers so they stopped any new members from joining.  I for have not received an email to get on to there forum even after being promised that I could over the phone anyway Geekzone is way cooler.

2Talk Faxmail - it works great, but not they way they say that it will. I have found that the only way it will work with any sense of reliability is to not registere the phone number in your ATA device so that all faxes go straight through to an email account - I thus need 2 phone numbers so I can use one number to send faxes which works fine on my brother fax machine which has a Voip setting.

My problem is that I need to get the faxes printed as they come in so I used a program called automatic print email #4 it works perfectly but its expensive $70 US dollars and the 30 day trial will soon run out.