This chapter deals with parametric multidimensional channel models, with the estimation of the corresponding parameters (such as delays, path weights and angles) from channel sounding data and with the metrological aspects associated to this processing chain. Deterministic and stochastic components of the channel model are discussed, focusing on decomposing the channel into a superposition of discrete multipath components and non-resolvable dense multipath components (DMC). Terahertz frequency bands readily enable the deployment of wide bandwidths; hence, models designed for narrow bandwidths need to be revisited and adapted. From a metrological point of view, the limits of parameter estimation need to be considered. It is shown how these limits relate to the choice of the sounding waveform and how they can aid in determining a reasonable number of propagation paths (model order selection).