  We investigate the amount of communication that must augment classical local
hidden variable models in order to simulate the behaviour of entangled quantum
systems. We consider the scenario where a bipartite measurement is given from a
set of possibilities and the goal is to obtain exactly the same correlations
that arise when the actual quantum system is measured. We show that, in the
case of a single pair of qubits in a Bell state, a constant number of bits of
communication is always sufficient--regardless of the number of measurements
under consideration. We also show that, in the case of a system of n Bell
states, a constant times 2^n bits of communication are necessary.
