If you want a pronounciation dictionary, then the cmu dictionary might be what you're looking for (125,000+ words plus phonetic transcriptions). You may have to adjust the mapping of phonemes to digits (it has separate phonemes for NG, for TH as in thee vs. TH as in theta). But it is certainly something you can work with to develop your data file of numbers to words --- I just did so in a few minutes.

Somewhat OT, but for those just looking for a large wordlist you might check out the yawl list available here, it has 263,533 entries ...by comparison, the stock /usr/share/dict/words file that came with my slackware distro has 38,619 entries. </p