The lattice parameters, lattice stability and phonon dispersion curves of five proposed phases of Ti: α, β, γ, δ and ω are investigated within density functional theory. It is found that the sequence of high pressure stable phases at zero temperature is α → ω → γ → δ → β. However, the γ phase may be unstable as is reflected by the existence of imaginary values in the phonon spectra. The results of the DFT calculations are employed to estimate the entropy and relevant free energies of the α and ω phases. It is found that converged phonon calculations lead to an entropy difference which is much smaller than that of previous estimates, casting doubt on the possibility of theoretical prediction of the α − ω phase transition line.