Using first-principles calculations and non-equilibrium Green’s function, we study the topologically-protected carrier transport in the edges of topological insulator ribbons. We investigate the effects of electron–phonon interactions on the edge state transport. We observed that in topological insulator with small bulk gaps, electron–phonon scattering results in the bulk states broadening into the bulk gap. This leads to the destruction of the dissipationless transport. However, if the transport is restricted to the protected states, a higher immunity to electron–phonon scattering can be achieved. This can lead to the design of topological insulator field effect transistors operating based on scattering modulation, benefiting from a channel material with strong electron–phonon coupling.