VoIP technology, when implemented in an internal corporate environment, has proven to be a huge success. This type of controlled environment promotes stability and reliability, as switching and routing can be monitored and managed to provide an excellent QoS. However, when dealing with home VoIP solutions, it is a different animal.
I work for an ISP that offers home VoIP through the use of an IAD (integrated access device). This type of service is much too reliant on the stability of the internet connection of our client. While the vast majority of our clients experience no problems at all, a small percentage complain about choppy or robitic voices when speaking on the phone. I had not even considered the possibility of virus activity, but it is true that the ones who do not have the QoS of the majority, are usually the same ones who consistently lose their internet connectivity by acquiring spyware, malware, backdoor trojans, etc. Some of the historical problem areas with cable service also experience the same effect. This is beyond the control of the ISP and raises difficult support questions to handle on the phone.
I have not elected to implement this in my own home. The solution does not provide 911 service due to the legal ramifications of a potential disconnection. It is an ideal solution for those who want to add a second line in their home, but it is difficult to sell when the client does not have internet service and they are considering the cost of a high speed connection in addition to the cost of the VoIP service.
PS-We have a lot of resellers of our service who are very successful. http://www.talknet.ca/