In this Letter, we study optical properties of all-solid microstructured optical fiber made of soft glass. Such fibers have various interesting features including good geometrical stability, low fundamental transmission losses, high Kerr nonlinearity, and large solubility of rare-earth ions. By investigating the transmission mechanism, mode structure, and numerical aperture of the fibers and confronting the results with theoretical calculations we demonstrate that the fibers have optical properties similar to those observed in air-silica microstructured optical fibers. This makes the all-solid soft-glass microstructured fibers very attractive for many potential applications.