VoIP will work on a 64 or 128k ISDN connection, however for good Quality of Service (QOS) a minimum of a 256k connection is recommended. These kinds of speeds can be achieved with DSL, Cable, 3G and Wireless networks. If you plan to use your internet connection for other kinds of data transfer at the same time as VoIP it would be highly recommended to get a connection speed greater than 256k and implement QOS within your network hardware to ensure consistent quality in VoIP calls.

While VoIP can work through a satellite connection the quality of the connection due to the inherent limitations of satellite broadband can result in a poor voice call quality, and as such a number of VoIP providers will indicate that they will not provide a service to satellite broadband based customers..

Test Your VoIP is a great free service for obtaining an indication of how suitable your broadband connection will be for VoIP based calls.

An excellent resource for helping to choose a broadband service and to gain user opinions about the network quality of various service providers is Whirlpool's Broadband Choice.