Internet access through the public switched telephone
network, PSTN/ISDN, produces changes in the characteristics
of traffic managed by this kind of networks. Under this
situation, traditional network dimensioning using Erlang model
results excessively optimistic. This article develops a simple model
to approach traditional methods to current PSTN/ISDN traffic
features including the effect of call repetition. The analytical
model obtained for traffic dimensioning is validated with simulation
models, and have been integrated in tools for design and
dimensioning of PSTN/ISDN networks