Abstract: A computer telephony server for simultaneously implementing a plurality of messaging applications is provided. The server includes a processor, a memory and a plurality of slots connected to the processor through a high-speed bus, each of the plurality of slots being adapted to receive an interface card for connecting the server to an external resource. A plurality of primary sessions are provided, each of which have a first thread of execution on the processor and control a first subset of the memory and at least one external resource. A plurality of secondary sessions, each corresponding to one of the primary sessions, is also provided. Each secondary session has a second thread of execution on the processor and controls a second subset of the memory. The primary session delegates a set of system resources to its corresponding secondary session and monitors the secondary session's behavior.