[mc_]

I'm confused; looking at the OpenVBX page, under requirements: Web Server MySQL 5+ PHP 5.2+ recommended Twilio Account (link to twilio)

[akalsey]

Automobile manufactures will tell you to use factory parts, too. Doesn't mean there aren't other compatible options.

OpenVBX would run on any platform that emulates Twilio's API. That includes Twilio (of course), Plivo, an Teleku (disclosure: now owned by us). There may be others out there as well.