Believe it or not, font files are considered copyrighted material and are not automatically available for all off-the-shelf systems. Some companies that utilize different fonts (other than standard fonts) may not be available to others unless they have "purchased" the same ones. AutoCAD may reference different fonts in its drawing files drawn by the originator but if that particular font file is not available in the next users system it will error or ask for a substitute which will most likely look very different that the original font. A request may have to be made to include the font files along with the drawing files that are being updated by another user.