  We report on room temperature phonon-assisted whispering gallery mode (WGM)
lasing in ZnO microwires. For WGM laser action on the basis of the low gain
phonon scattering process high quality resonators with sharp corners and smooth
facets are prerequisite. Above the excitation threshold power $P_{\textit{Th}}$
of typically $100\,kW/cm^2$, the recombination of free excitons under emission
of two longitudinal optical phonons provides sufficient gain to overcome all
losses in the microresonator and to result in laser oscillation. This threshold
behavior is accompanied by a distinct change of the far and near field emission
patterns, revealing the WGM related nature of the lasing modes. The spectral
evolution as well as the characteristic behavior of the integrated
photoluminescence intensity versus the excitation power unambiguously prove
laser operation. Polarization-resolved measurements show that the laser
emission is linear polarized perpendicular to the microwire axis (TE).
