# High Availability A modern unified communications system is much more complicated than the phone system of 25 years ago — most likely, it’s now running on commodity PC, Server, and cloud platform infrastructure rather than a custom-built hardware chassis. It’s now connected to the Internet, and probably sends calls across the network as well, instead of having dedicated analog or digital lines for each extension and for each connection to the outside world. When installing a modern unified communications system, the topic of resiliency is often of high importance. Customers expect their unified communications system to be resilient, despite the ever-increasing complexity. With PortSIP PBX and PortSIP UCaaS solutions, PortSIP is glad to give the HA function, which allows it to take over in the event that the server fails. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://support.portsip.com/pbx_v12/portsip-uc-high-availability.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.