Published online by Cambridge University Press: 20 November 2018
Let $\mathcal{T}$ be the
${{C}^{*}}$-algebra generated by the Toeplitz operators
$\left\{ {{T}_{\varphi }}:\varphi \in {{L}^{\infty }}\left( S,d\sigma \right) \right\}$ on the Hardy space
${{H}^{2}}\left( S \right)$ of the unit sphere in
${{C}^{n}}$. It is well known that
$\mathcal{T}$ is contained in the essential commutant of
$\left\{ {{T}_{\varphi }}:\varphi \in \text{VMO}\cap {{L}^{\infty }}\left( S,d\sigma \right) \right\}$. We show that the essential commutant of
$\left\{ {{T}_{\varphi }}:\varphi \in \text{VMO}\cap {{L}^{\infty }}\left( S,d\sigma \right) \right\}$ is strictly larger than
$\mathcal{T}$.