Here is an old AutoCad trick that works with AutoCad fonts (not TrueType) as well as splines and ellipses. This process will convert those entities into lines and polylines that most programs should import.
1) Export the drawing as a Windows Metafile. (use export or "WMFOUT").
(NOTE: For better resolution before the export, zoom in close on any entity in the drawing, do a regen, and then a "zoom previous". (may not matter on newer versions of ACAD)
2) Now import the WMF file into a new drawing using the "IMPORT" command.
3) Entities will come in as blocks which you can now be exploded into lines and polylines.
4) This process usually changes the size of everything so you may need to re-scale them. Make sure you know the dimensions of something in the drawing to use as a reference, or add a line of known length to the original drawing and delete it when you are done.