OpenVBX has a plugin system that allows developers to extend its functionality in powerful ways, with the opportunity to win prizes for submitting an OpenVBX plugin or improving an existing one. The contest is part of Twilio's efforts to encourage developers from all backgrounds to try the platform and solve problems with it. Submissions can be submitted online by a deadline of July 3rd, and resources are available on Twilio's website to help developers get started and improve their skills.