Had Comcast Digital Voice over 2 years Ken after 5 months of putting up with Version billing issues. I am very pleased with it, note you need to keep one phone plugged into into the phone wiring that does not need AC power to operated IF you want service during power outages - it will give you roughly 8 hours backup time. We mostly have base units with drop in handheld phones and when you lose house power, the drop in base stations go dead - so we keep one standard older push-button desk kinda phone in line too for outages.
I was one of those "I'll never go VOIP cause the technology isn't there guys," but seriously glad I did and I have not had an issue to date.
Mind you too, Comcast understands the economy and in decades of having them, when "Promotional deals are up" I simply state I need the same deal again - typically 1 year of triple play at $119 a month plus $20 for two movie channels (HBO and SHOWTIME) plus cable modem rental - $149 for 12 months, over and over again.
Considering we were paying almost $50 for a landline prior and still paying about the same for cable as we do now, the triple play made our phone bill free ( included any ways) and we pocket the $50.
So saving $600 a year to have our phone with the same number we've had since 1964 using Comcast is a awesome deal.