How does Simulink handle time delays, with ODE or DDE solver?

I have implemented feedback control systems with fixed time delays using both MATLAB scripts and Simulink, and they behave similarly. The MATLAB scripts use the dde23 delay differential equation solver which can handle time delays. The Simulink model has time delay blocks in the control system, and the solver is set to ode45. My question is whether Simulink is still using ode45 for control systems with time delays? Could it be using a delay differential equation solver when there are time delay blocks in the system, or approximating it use Pade approximations while solving the equations?

Appreciate any help.