  The Kerr/CFT correspondence is a possible route to gain insight into the
quantum theory of gravity in the near-horizon region of a Kerr black hole via a
dual holographic conformal field theory (CFT). Predictions of the black hole
entropy, scattering cross-section and the quasi normal modes from the dual
holographic CFT corroborate this proposed correspondence. More recently, it has
been suggested that quantum gravitational effects in the near-horizon region of
a black hole may drastically modify the classical general relativistic
description, leading to potential observable consequences. In this paper, we
study the absorption cross-section and quasi normal modes of a horizonless
Kerr-like exotic compact object (ECO) in the dual CFT picture. Our analysis
suggests that the near-horizon quantum modifications of the black hole can be
understood as finite size and/or finite $N$ effects in the dual CFT. Signature
of the near-horizon modification to a black hole geometry manifests itself as
delayed echoes in the ringdown (i.e. the postmerger phase) of a binary black
hole coalescence. From our dual CFT analysis we show how the length of the
circle, on which the dual CFT lives, must be related to the echo time-delay
that depends on the position of the near-horizon quantum structure. We further
derive the reflectivity of the ECO membrane in terms of the CFT modular
parameters, showing that it takes the Boltzmann form.
