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.
Activabilling VoIP Solutions is offering free customization in any panel (upto 3 requests) to change or modify any feature in its Control Panels or IVR solutions.