Very interesting. I can See that you haven't assigned /w/, /j/ and /h/, is that intentional? Also, what happens when a word only has vowel phonemes, like 'eye'?
Indeed /w/, /j/, and /h/ are not assigned any numbers in this system. I believe the intention was to omit sounds that are phonetically too similar to vowel sounds.
A word composed entirely of vowel sounds are not used in this system.