| When the user picks up the IP Phone and dials the destination number, VoIP Gateway sends an authorization request to VoIP Billing. |
| VoIP Billing verifies user account information and authorizes the call if the user has sufficient balance. |
| VoIP Gateway passes the destination number to uniSwitch Softswitch and requests routing information. |
| uniSwitch returns to VoIP Gateway the IP address of the remote (termination) gateway andVoIP Gateway connects to it. The remote gateway terminates the call to the destination party. If the call is to another subscriber of the same service provider, VoIP Gateway terminates the call directly. |
| Upon call completion, VoIP Billing records complete CDR information for the call and debits the user account with accumulated service charges. |