The least expensive VoIP services cost under $10 per month in service fees for residential use. Business VoIP services can cost considerably more depending on the number and types of features they offer. Taxes and fees pertaining to your locality also apply. Look for a VoIP service that doesn't charge a high amount for the hardware. Services that provide free calling or free hardware do exist, but are somewhat rare. Avoid contracts whenever possible so you have the option of switching to a new service on your own terms.