Voice over Internet Protocol phone systems use Session Initiation Protocol, or SIP, to manage voice connection routing when connecting to a broadband telephone network. When creating your own PBX or VoIP server, you must correctly configure the SIP settings to connect to a service provider network and negotiate calls with other VoIP or landline telephone systems. SIP settings allow you to use hardware or software IP phones with your VoIP system and ensure that all phones connect to the network in the same way. Configuring phones and systems for use with SIP used to be a tedious process, but modern VoIP PBX software makes the task much easier and straightforward.
Install Linux on a dedicated server computer. Connect the server to a broadband router to access the Internet. Download and install a free PBX/SIP/VoIP server application (see Resources). Most VoIP server applications come as image files that you must burn to a CD or DVD.
Open the CD/DVD authoring/burning program on the Linux computer. Burn the VoIP server image file to a blank CD or DVD.
Launch the installation utility on the new CD or DVD. Wait for the installation wizard to appear on the screen. Follow the installation wizard to install the VoIP server software. Reboot the computer if prompted to do so.
Subscribe to an account with a VoIP service provider that allows you to use your own hardware IP phones or software phone applications. VoIP providers like VoIP.ms, Broadvoice and Teliax have plans for individuals or small office VoIP networks that allow you to use open source software to access the service provider's VoIP gateway (see Resources).
Print out your account information, including your assigned phone number, VoIP gateway IP address, username, password and authentication code.
Launch the SIP/VoIP server software on the Linux computer. Click the "VoIP Settings" or "Connection Settings" option on the menu or tool bar. Enter your VoIP account information, your phone number, account username and password.
Enter the authentication code in the "Pin" or "Code" field and save the account configuration settings. Enter the assigned VoIP Gateway IP address in the corresponding field.
Click the "IP Settings" or "Internet Settings" menu option. Jot down the IP address shown in the "Server IP Address" field.
Connect the included RJ-45 LAN network cables to the IP phones and broadband router. Optionally, download and install software IP telephone applications to use with the VoIP provider network.
Configure the IP phones or soft-phone software with the SIP information for the local VoIP server. Enter the IP address information for the local SIP server in the "192.168.0.1" format.
Reboot the new SIP/VoIP server computer. Launch the VoIP server software. Wait for the server software to connect with the VoIP service provider and establish a connection.
Use the hardware IP phones or phone software to place and receive calls using the new VoIP server and the service provider's gateway.
Ensure the Linux VoIP server computer uses a static IP address and not a dynamic address assigned to it by the broadband router. Refer to the user manual for the SIP/VoIP server application for information on how to set up departments and extensions or to route calls to various computers or IP phones on the network.