The objective of this work is to estimate by inverse problem lip parameters values of trumpet model so that the oscillation thresholds for successive playing registers occur for the same blowing pressure as the one measured on several trumpet players. The lips vibration is modeled through an oscillator including unknown parameters such as resonance frequency, quality factor, surface mass, stiffness, and opening at rest of the lips. The oscillation threshold is calculated through linear stability analysis of the outward-striking model including the nonlinear coupling with the bore of the trumpet. It appears that many combinations of parameter values are suitable to obtain the same blowing pressure at threshold as in the experiments. According to the analysis of the possible parameter values, some hypotheses are formulated about the playing strategies used by the trumpeter to select the different registers of the instrument. In addition to the resonance frequency of the lips, controlling the lips opening at rest appears to be a viable strategy to match experimental oscillation thresholds in terms of blowing pressure. Numerical values for the lips parameters are given and through sound synthesis, allow the successive registers of the trumpet to be played.