1. A system for providing third-party call control comprising: a single call-control server connected to both a dedicated connection-oriented switched telephony (COST) network and to a data-packet network; a control application executing on the single call-control server from a non-transitory physical medium, the control application comprising a single call model, the attributes of the single call model defined in low-level descriptor language, providing service-logic description and connection request command instruction as primitive text for implementing call connections in either of the networks; and a first call-routing switch in the COST network enabled to execute the primitive-text commands and accessible to the single call-control server, and a second call routing gateway in the data-packet network, enabled to execute the primitive-text commands and accessible to the single call-control server; wherein the single call-control server using the control application sends the primitive text commands to both the first call-routing switch and the second call-routing gateway utilizing the single call model, and wherein both the first call-routing switch and the second call-routing gateway receive, read and implement the text commands containing all of the service logic and instructions required to successfully construct call connections, and wherein the first call-routing switch and the second call-routing gateway each send notification of success or failure regarding implementation of received commands back to the control application.