When you receive an incoming call to your phone number, your other telephones (cell, home phone, car phone) will ring as well and the first one answered will be connected to the caller. Basically the call will be routed to all phone sets, which you will list in simultaneous ring option.
At SIPRoutes.com we have pioneered a new way to source SIP Termination providers. By creating a marketplace with every major vendor available, our customers choose the vendors that meet their quality and pricing requirements.