> 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/v16.x-maintenance-mode/pbx-cluster.md).

# PBX Cluster(v16.x)

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This topic is only applicable to the PortSIP PBX v16.1 and later versions.
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This topic describes how to deploy the PortSIP PBX with cluster support for up to 1M+ users, \~50,000 online users(registered users/signed-in users), and \~10,000 simultaneous calls, support more meetings, and IVR, queue calls.

This article includes the following topics:

* [Topology](/v16.x-maintenance-mode/pbx-cluster/topology.md)
* [Preparing Cluster Servers](/v16.x-maintenance-mode/pbx-cluster/preparing-cluster-servers.md)
* [Configuring Cluster Servers](/v16.x-maintenance-mode/pbx-cluster/configuring-cluster-servers.md)
* [Managing Cluster](/v16.x-maintenance-mode/pbx-cluster/managing-cluster.md)
* [Configuring Cluster Servers for High Availability](/v16.x-maintenance-mode/pbx-cluster/configuring-cluster-servers-for-portsip-pbx-ha.md)