In this note, we clarify the relationship between the two-point Carrollian correlator and massless scattering in black hole background. It turns out that there are two kinds of Carrollian correlators at the null boundaries of each asymptotically flat spacetime. The correlator from I [−] to I [+] should be regularized by subtracting the flat space analog, and it is the position space version of the reflection amplitude of massless scattering. On the other hand, the correlator from I [−] to the future horizon H[+] is absent in flat space, and it is the position space version of the transmission amplitude. The poles of the Carrollian correlators are governed by the null geodesics from I [−] to I [+] or H[+], and these geodesics define two classes of classical equations in Carrollian space. These equations relate the Shapiro time delay to the deflection angle and are determined purely by the boundary data. We find that, for small deflection angles, the time delay for the correlator from I [−] to I [+]/H[+] exhibits logarithmic/quadratic behavior. On the other hand, when the deflection angle is large, the time delay always increases linearly for both correlators. We further establish a relation between the low-frequency bulk scattering coefficients and the leading non-contact contributions at late times. The correlator from I [−] to I [+] features an inverse-square tail τ^{−2} with an explicit angular distribution K_2. We have numerically confirmed this angle-dependent late-time tail.