The aim of this paper is to derive the analytical solution of the non-truncated single-channel Erlangian queue: M/E k /1 at the steady-state with adding the concepts of balking, feedback strategy and retention of reneged customers. We obtain the probabilities that there are n customers in the system and the customers in the service occupces stage s, (s = 1, 2, …, k), the probability of empty system and some measures of effecting of queuing system are obtained using the iterative method. Some important queueing models are derived as special cases of this system. Some numerical values are given showily the effect of correlation between the probabilities and the additional concepts.