“…The methods applied in queueing theory are used to analyze the model, which is described by a queueing system (QS) with a buffer and its retrial group [2,6,8,12]. We assume that if there is free resource, the elastic session will be established upon arrival, otherwise it will await in the buffer, from where it can depart for buffer' retrial group [3,8,14,15,17] and return after a moment.…”