In general, the installation process consists of the following steps:
Download and install Asterisk PBX (if you don't have it deployed).
Download and install Odoo (if you don't have it deployed).
Configure Odoo for the OdooPBX modules.
Download and install OdooPBX modules.
Install the Agent middleware (Agent acts as a bridge between Odoo & Asterisk).
Configure Odoo to access the Agent (PBX -> Settings -> Server).