Your choice of a VoIP service provider will have the greatest impact on the quality of service you receive and the ease of your transition from a standard phone system. VoIP has exploded in popularity in just a few short years. The number of providers has also increased accordingly, making it imperative that you do some research on the support and practices of each potential provider.
VoIP is a relatively new service, but it springs directly from changes within the traditional telecommunications industry. The major telcos route analog phone calls to digital switching stations, where the signal is converted to digital packets. These packets are the routed through the network to another switching station near to the call recipient. The digital packets are then converted back to analog and sent the rest of the way along the old analog lines.
VoIP phone systems simply convert your voice to digital packets via the VoIP receiver or (or by using an analog telephone adapter (ATA) attached to a common telephone). The digital signal is then sent either to the appropriate digital switching station for conversion back to analog (in the case the call recipient does not use VoIP) or directly to the IP address of the call recipient (if the recipient also uses VoIP).
Since VoIP service providers convert voice signals to data packets, and data transmissions have far more available bandwidth, long distance and international calling can be done at greatly reduced costs. However, factors like network security, the need for technical support, call quality, and service reliability should be your main concerns when choosing a provider.