Without -d[options] listed above, ps2pdf will not embed and subset fonts as required by PDF compliance and your paper will not be ready for upload. Note that if you specify the Adobe Times, Helvetica and Courier font families (the so-called base 14 fonts) to be used but do not have them installed on your computer then they will not be embedded. Pdf files with these fonts missing may or may not be accepted depending on the conference settings; they often are.