OpenVox provides superior quality FXO/FXS analog cards with most advanced features and optional hardware echo cancellers to extend the functionality of Asterisk® to connect the Public Switched Telephone Network (PSTN). A large number of custom telephony solutions are made possible with this powerful combination of OpenVox hardware and Asterisk open source software. The OpenVox analog cards enable our customers to build the leading PBX, IVR and call center applications worldwide.