This paper presents the derivation of maximum likelihood estimates for the arrival rate and service rates in a stationary M/M/c queue with heterogeneous servers. Although previous works facing the problem can be found in the literature, all of them are only valid under the assumption of transferring of customers in service. A more realistic approach for many systems is developed in this paper. This model considers the customers are attended by the available faster server and there is no transfer of customers among servers. The model can be applied in a large variety of systems such as production systems, banking, cyber café or taxi station.