When a solid melts and produces liquid, the process occurs at the melting point of the solid. For example, ice melts at 273 K and produces water at the same temperature.
H2O (s) → H2O (l)
The heat involved in the process of melting is called enthalpy of fusion (ΔfusH).
ΔfusS = ΔfusH/T
Similarly for vaporization at the boiling point,
ΔvapS = ΔvapH/T