How to Install Asterisk on CentOS 7

Installing Asterisk 13 on CentOS 7

Deploy VoIP Services with Asterisk and Freepbx on Ubuntu 12.04

Install Asterisk and FreePBX on Your Linux VPS to Use and Manage a Telephone Exchange.

Install and Configure Mumble on Debian

Mumble is an open-source, encrypted VoIP software. This guide instructs how to install the Mumble server on Debian and gives general guidelines for configuring the Mumble client.