> For the complete documentation index, see [llms.txt](https://support.portsip.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.portsip.com/portsip-communications-solution/pbx-cluster-v22.md).

# PBX Cluster (v22.x)

This guide explains how to configure cluster servers for a standalone PortSIP PBX deployment, designed to support over 1 million users, approximately 50,000 online (registered/signed-in) users, and up to 10,000 simultaneous calls. The setup is also well-suited for high-demand scenarios, including large meetings, IVR, and call queues.

If you've already deployed your PBX in High Availability (HA) mode and wish to expand to a cluster configuration, please refer to the guide in [**High Availability (v22.x)**](/portsip-communications-solution/high-availability-v22.x.md).

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This article includes the following topics:

* [Topology](/portsip-communications-solution/pbx-cluster-v22/topology.md)
* [Preparing Cluster Servers](/portsip-communications-solution/pbx-cluster-v22/preparing-cluster-servers.md)
* [Configuring Cluster Servers](/portsip-communications-solution/pbx-cluster-v22/configuring-cluster-servers.md)
* [Managing Cluster](/portsip-communications-solution/pbx-cluster-v22/managing-cluster.md)