The SPA9000 marries the rich feature set of legacy PBX telephone systems with the convenience and cost advantages of Internet telephony. It has common key system features such as an auto attendant, shared line appearances, three way call conferencing, music on hold, "follow me" calling, and many more. The SPA9000 opens up access to the benefits of Voice Over IP, including low cost long distance service, phone number portability, and one network for both voice and data. 

The SPA9000 is so easy to configure that a fully working system can be setup up in minutes. New phones are automatically detected and registered when they are connected to the SPA9000. The SPA9000 has an integrated web server that allow features to be configured using a web browser. The web server has multiple levels of password protected access to user and service level features. Service level settings may be locked by the Internet Telephone Service Provider to ensure they are not 
accidentally corrupted. The Service Provider can remotely update the software and 
settings through a secure encrypted connection. 

With it's integrated router, the SPA9000 can be either connected directly to the internet connection, or connected indirectly through another router. The SPA9000 has separate WAN and local network Ethernet ports. The WAN connection can be connect through DHCP, a fixed IP address, or through DHCP. The LAN port can assign IP addresses to IP telephones and computers using NAT and DHCP. While the SPA9000 will work with any SIP compatible IP telephone, it is the ideal host for Linksys business telephones, such as the SPA941, SPA942, and SPA962. With little additional configuration, the SPA9000 supports the advanced features of these phones, such as shared line appearances, hunt groups, call transfer, call parking lot, and group paging. With its two FXS ports, the SPA9000 can support traditional analog devices such as telephones, answering machines, FAX machines, and media adapters.