Low price is still the main driver for international VoIP according to research firm TeleGeography.
Broadband-based VOIP services to homes and businesses can include added features such as click-to-dial and a choice of area codes.
Call quality on VOIP has also improved significantly, according to TeleGeography. However, the research company said new features and quality aren't the main motivations for international VOIP.
Most international VOIP calls are made to countries in the developing world, using conventional phones, in order to bypass regulated termination charges for circuit-switched calls.
International VOIP traffic grew by 35 percent to 30.8 billion minutes in 2004.
Though the growth rate has dipped from more than 100 percent per year in the early days of the technology, usage seems to be increasing.
The top three countries for VOIP growth in 2004 were