Before revision:  The system stability condition and probability generating functions  of the number of calls in orbit and system are derived and evaluated numerically in the context of mean system size, server availability, failure frequency , and orbit waiting time.
After revision:  The system stability condition and probability generating functions of the number of calls in the orbit and the state of the server are derived and evaluated numerically in the context of mean system size, server availability, failure frequency , and orbit waiting time.