A high speed 1-1/2 axial compressor stage is simulated in this paper using an Unsteady Reynolds-Averaged Navier-Stokes (URANS) solver for a full-annulus configuration to capture its non-synchronous vibration (NSV) flow excitation. The simulation presented in this paper assumes rigid blades. A 3rd order WENO scheme for the inviscid flux and a 2nd order central differencing for the viscous terms are used to resolve nonlinear interaction between blades and fluid flow. A fully conservative rotor/stator sliding boundary condition is employed with multiple-processor capability for rotor/stator interface information exchange for parallel computing. The sliding BC accurately captures unsteady wake propagation between the rotor and stator blades while conserving fluxes across the rotor/stator interfaces. The predicted dominant frequencies using the blade tip response signals are not harmonic to the engine order, which is the NSV excitation. The simulation is based on a rotor blade with a 1.1% tip-chord clearance. Comparison to previous 1/7th annulus simulations show previous time-shifted phase-lag BCs are accurate. The NSV excitation frequency of the full annulus simulation is for the most part 3.3% lower than experimental and matches with the 1/7th annulus simulation, although some blades displayed slightly different NSV excitation frequencies. The full annulus simulation confirms that the instability of tornado vortices in the vicinity of the rotor tip due to the strong interaction of incoming flow, tip vortex and tip leakage flow is the main cause of the NSV excitation. This instability is present in all blades of the rotor annulus. While the time-shifted phase lag BCs can accurately capture the frequency of NSV excitation, phenomena related to flow separation with lower frequencies, including dual-vortex systems within blade passages, are not captured by the 1/7th annulus simulation, but are found in the full-annulus simulation.