Abstract: Systems and methods for providing configurable, reusable software-implemented telephony devices for use in a voice over Internet protocol (VoIP) system. A device platform data store associates account owners with information identifying at least one instance of a telephony device provided on behalf of the account owner. The instances are implemented via a computer program component which comprises (a) reusable device logic (in a CCXML document) defining the behavior of the telephony device and (b) configuration information (also in a CCXML document) comprising specific device properties for the telephony device. In response to an incoming communication, a processor accesses the device platform data store to identify the device logic of a telephony device that is to be activated, and (b) executes the device logic in accordance with the configuration information to provide the specific telephony function of the telephony device for a communication session on behalf of the account owner.