astrofan-
I am just taking my chances, but my wife (usually home with 6-month old infant) has adequate backup anyway (cell, other per minute VOIP.) A friend of mine uses the Find-Me-Forwarding method (using his own answering machine instead of SRs voicemail) and we tried it out. Works very well. When he unplugged the gizmo from the wall calls were just routed to the next number on the Find-Me-Forwarding list, his cell. The thing about failover is that during every big outage from VOIP providers with failover in place it does not seem to work. When Voicepulse had several outages in a short time span the lack of failover (despite it being one of the features) was discussed. Same with Vonage's very long outage in August. Seems like when the provider has a big problem on their end failover does not work anyway in most cases. It does come in handy, though, if you have an internet problem or power outage at your house. All it takes is for someone cleaning up to inadvertantly unplug the electricity to your router or gizmo. That's where failover would come in handy the most, IMO.
You are right, uptime has been terrific, at least when we picked up the phone to attempt a call. With everybody here knowing not to mess with my gizmo/router/cable stuff lacking failover hasn't been an issue.
jodigby-
Quoting:
"the signature number is a destined number that you choose so that other people that may live away from you can dial a number that is local to them but will still ring up your phone."
SR calls this the ANYWHERE NUMBER. However, you may also just select a local signature number to have as a dedicated fax line or so-called teenager line. You can select distinctive ring for that number, which comes in handy for fax machines that can understand distinctive rings. Or for the person in your household running to the phone because the special ring signals that her/his school buddies are calling.

Not that unlike other VOIPs, Sunrocket's signature number comes with its own voicemail box and all features activated (such as call forwarding, call blocking, etc.)
gtfan-
I called SR up last week to ask about these issues. I was told that one could get the 15 month/$199 deal by calling them, even though it was no longer offered on the website. The same applies to the $100 int'l calling card deal. Someone with a gizmo (given to them by a friend) can call in and activate the $9.95 per month deal without incurring the $40 equipment fee. I was also told that if I wanted to I could sign up for the 15 month/$199 deal as an existing customer. I am not up for renewal yet (that is in March,) so it would not make any sense for me at this point.