Complex sentence: In this case a large number of people would simultaneously phone the number provided, and if the service provider has not catered for this sudden peak demand, extreme traffic congestion will develop and Erlang's equations cannot be used (1).
Split into simpler sentences: In this case a large number of people would simultaneously phone the number provided. If the service provider had not catered for this sudden unanticipated peak demand, extreme traffic congestion will develop and Erlang's equations cannot be used (1).