How to Install Asterisk on CentOS 7

Installing Asterisk 13 on CentOS 7

Deploy VoIP Services with Asterisk and FreePBX on Ubuntu 12.04 (Precise)

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.