VoIP is a reliable technology, particularly since it is fairly new. A simple answer to this question is yes, VoIP is just as reliable as the Internet. But there are a few considerations with this issue, and this article will briefly discuss these.
The Internet, as a method of communications, is very reliable. There have only been a couple of instances in the recent past where the Internet was “down”. These instances both involved email “worms”, and actually only slowed response time to a crawl. The Internet was still “up”, it was just overwhelmed. The major reason for this reliability is that the Internet was specifically designed to provide a method of communications during large-scale natural or man-made disasters. The Internet has built-in redundancy, and its basic design is one that makes it almost impossible for it to be disabled. So as far as VoIP is concerned, there is little doubt as to the reliability of the medium being used to carry your calls. Most of the reliability issues of VoIP have to do with either an individual service provider or with the VoIP equipment that you may be using.
VoIP does require a service provider presence on the Internet in order to function. So the reliability of your service will depend on the ability of your service provider to maintain this presence. Most providers have considerable redundancy built into their servers and other hardware. This means that if they do experience a problem, you will likely never be aware of the fact. Their backup systems are designed to take over almost instantly in the event of a failure, so it is likely that the worst problem you would experience would be a slight interruption in service. This would be similar to a call “breaking up” or being “dropped” by a cell phone, but is not nearly as likely to happen with VoIP as it is with cell phone service.