1. A method comprising: a multi-tenant telephony system managing a plurality of applications provided by a plurality of application servers external to the telephony system; a call router of the telephony system generating an event of a first application of the plurality of applications during the management of the first application by the telephony system; the call router publishing the generated event to an event router of the telephony system; the event router sending the published event from the event router to at least one subscriber to the published event, wherein each application of the plurality of applications controls interaction between a telephony device and the call router.