Abstract: By computer simulation we found a phenomenon of “callssqueezing out” in ATM networks under the traffic approaching to the system capacity when using simply the CAC algorithms proposed in the past, i.e. the narrowband services calls blocking the wide band services calls into networks. We studied and proposed a simple calls access balancing machinery, and analyzedthe access probabilities of various kinds of calls and the probabilities of thenarrow band services calls blocking the wide band services calls into networksunder the machinery.

Key words: ATM, call admission control, call, block, probability