A method and apparatus for providing a telephone operating company with the ability to rapidly deploy advanced services into a public switched telephone network includes a programmable service node interacting with a programmable switch matrix. The call processing of a call (associated with one or more ports on the programmable switch matrix) is controlled externally when particular triggering criteria is met (i.e., the call requires or desires external control). When the triggering criteria is met, the service node outputs a new call event notification message over a communications link to an external unit and receives one or more messages over the same link. Call control processing is achieved through this high-speed communications link between the programmable switch matrix and the external unit using a communications protocol defining a comprehensive set of primitives (instructions) for call manipulation and control at the programmable switch matrix which are received by the programmable service node. The one or more received messages include instruction data for instructing the programmable switch matrix to perform one or more actions associated with the service call, such as connecting a port with another port within the switch matrix. The service node processes the instruction data and instructs the switch matrix to perform the appropriate action(s).