Asterisk
Asterisk is a compact software implementation of a telephone PBX (private branch exchange). It allows attached telephones to make calls to one another, and to connect to other telephone services including the public switched telephone network and voice over internet protocol (VOIP). Asterisk is a mature, well-maintained software available under the GNU General Public license, and it carries support for a variety of popular VOIP protocols inclduing Session Initiation Protocol (SIP) – a protocol most commonly used by modern VOIP service providers.
Black River prefers Asterisk due to its combination of relative ease of deployment for simple applications and a wide array of features when deep customization is a requirement. Asterisk Gateway Interface (AGI) is a robust application programming interface which enables third-party applications such as CRM systems to integrate into the phone system and gain direct access to Asterisk’s features and data streams. An Asterisk application can be deployed on the majority of platforms to fit an existing infrastructure, and it carries none of the entry and licensing costs of hardware PBX solutions.