Containing the effects of long holding times due to Internet dial-up connections

Internet dial-up calls have much longer holding times than voice calls. We show that in their presence, classical engineering procedures become inadequate and, without control, economies of scale get impaired. Uncontrolled systems will suffer periods of unavailability due to persistence of congestion. For digital loop carrier systems with concentration, no-dial- tone situations impacting even critical services can obtain. Call admission and overload controls that maintain good performance and high utilization are also presented.