TerraSip is a mobile VoIP provider that allows customers from all around the globe to communicate with each other — absolutely free! There is no cost and no obligation for a TerraSip membership; there are no subscription or cancellation fees. The person you call only needs a copy of TerraSip's softphone software.
TerraSip also offers a variety of low international rates (the company went into business to lower long distance and roaming rates between European countries). Just credit your TerraSip account and you'll be able to make calls to anyone in the world. They just need to have a telephone.
TerraSip also offers wholesale rates and connections. Using SIP (session initiation protocol) and a variety of codecs, TerraSip provides its customers with easy and unlimited access to low calling rates, without contracts or monthly volume requirements.