Every telephone number will receive a SIP? address. This is designed to allow a person anywhere in the world with a SIP compliant service to call you just by knowing your SIP address. You can turn this feature off in the control panel, however your phone number @pcs1.ws will be your SIP address. For example for +1 4123608462 will be sip:14123608462@pcs1.ws. And since the person calling your SIP address will likely be free for them, they can reach you with your preferred SIP address, and you can communicate with them easily. PCS1 will also try to work with SIP Brokers to connect with their service to be more flexible.