The heating of phenyl-methyl ethers with $\text{HI}$ produces:

In phenyl-methyl ether (Anisole), the bond between Oxygen and the Phenyl ring has partial double bond character due to resonance. Thus, the ${\text{I}}^{-}$ nucleophile attacks the smaller methyl group via an $S_{N}2$ mechanism.${\text{C}}_6{\text{H}}_5-\text{O}-{\text{CH}}_3+\text{HI}\to {\text{C}}_6{\text{H}}_5-\text{OH}+{\text{CH}}_3\text{I}$.The products are Phenol and methyl iodide.