  We consider generalisations of the dense coding protocol with an arbitrary
number of senders and either one or two receivers, sharing a multiparty quantum
state, and using a noiseless channel. For the case of a single receiver, the
capacity of such information transfer is found exactly. It is shown that the
capacity is not enhanced by allowing the senders to perform joint operations.
We provide a nontrivial upper bound on the capacity in the case of two
receivers. We also give a classification of the set of all multiparty states in
terms of their usefulness for dense coding. We provide examples for each of
these classes, and discuss some of their properties.
