Search for: [Description = "The design and optimization process of modern telecommunications networks is supported by a range of appropriate analytical models. A number of these models are based on the Erlang’s Ideal Grading \(EIG\) model, which is a particular case of non\-full\-availability groups. A possibility of the application of the EIG model results from the fact that telecommunications systems show properties and features distinctive to non\-full\-availability systems. No detailed studies that would decisively help determine appropriate conditions for the application of the EIG model for modeling of other non\-full\-availability groups, that would be models corresponding to real telecommunications systems, have been performed. Therefore, this article attempts to find an answer to the following question\: what are the prerequisite conditions for the application of the EIG model and when the model can be reliably used\?"]