(Originally left as a comment on Om Malik's Gigaom.com website)
Wow - I'm shocked.
Not at the fact that SunRocket finally kicked the bucket, but at Om's reaction. Now, for the sake of full disclosure, I do work for an "Independent VoIP" provider. This is why I find the cry to "Stay Away from Independent VoIP Providers" a little shocking.
The problem isn't that SunRocket was an Independent VoIP Provider, the problem was a losing business model. Because SunRocket required users to have SunRocket hardware to access their network, it added a significant amount of overhead to their operations (hardware support, warehousing, pre-purchasing, customizing). Add in carrier fees such as DID number reservations as well as the normal business expenses and the margin is already very low.
Then we get to the whole "unlimited minutes" issue, which was the nail in the coffin. Bluntly, unless you have a sufficient number of customers so you can do real capacity analysis, the flat rate model is risky at best as the upstream carriers who handle the PSTN -> SIP gateways are charging per minute. If you're off on your estimation of how much people will use the service, you can end up not just losing a little money, but bleeding dollars. I would assume that SunRocket made some bad assumptions and ended up paying the price.
Then again, the users who went to SunRocket were looking for that "Unbelievably Good deal" and you know what they say - if it's too good to be true, it probably is. Now, this isn't to say that it's impossible or even marginally difficult to build a sustainable business plan as a VoIP provider. Requiring specific hardware? Not a good idea - sure it's easier for the client to set up, but a good instruction sheet and a list of supported (or just recommended) SIP Phones/Softphones reduces the overall overhead for the provider.
Shifting from "unlimited" minutes to reasonable per-minute rates with bulk pre-purchasing discounts so you can truly understand your costs is critical as well. Will it be as sexy of a service? No. It won't get the sort of press that an unlimited service can provide. But it will create sustainable revenue and a path towards becoming cash positive. Then, instead of focusing on undercutting the competition by a dollar a month, focus on building innovative services and applications for your users. A profitable VoIP provider with a robust set of apps? Call me crazy - but that's the sort of sexy vendor that this industry needs.