FoonzMobile is a free service that allows users to instantly create and invite members to a group based conference call through SMS text messages[via BusinessWire]
To start a foonzMobile call, all you need to do is send an SMS to 36669 (foonz) with the text START. foonzMobile will reply with the text instructions on how to start the call. When the user initiates the call, foonzMobile sends instant invitations to participants via SMS to their cell phones with the session details. Participants can then simply dial the number in the invitation to join the call and foonz connects everyone together, automatically. If some contacts aren’t available, the call initiator can leave a message for them. Those contacts receive a text message letting them know they have a message waiting and instructions for retrieving it.
Registered users can import contacts and then start instant group calls with anyone on their contact list by texting START and the names of the people they want to talk with