Abstract The effect of the strong coupling of multiphonon states on the fusion of heavy ions is discussed. The model (CCFUS) of Dasso and Landowne is reviewed and it is shown that it is possible to generalise this to multiphonon states comprised of identical phonons without greatly complicating the calculations. The effect of the muliphonon channels on the barrier distribution for fusion is discussed in detail. In particular, it is shown that for such a system, one barrier may be pulsed up to rather high energies. This high-energy barrier will be difficult to see in the fusion data but we show that it may have a significant effect on the large-angle elastic (or quasielastic) excitation functions.