This is a clever idea, but I don't think it will fly; at least not in most places.
Human phonemes exist in a continuous N-dimensional space. There are two problems to defining a universal phonetic set:
1) different populations use different areas of the space. For example, some cultures use hardly any vowels, some hardly any consonants.
2) different populations quantize the space at different boundaries. So even two cultures who both have 5 vowels may find that what is unambiguously 'e' in one culture is 'a' or 'e' in another.
And those are just the major problems.
The usual solution is to have a set of glyphs that the are labeled in a locally distinguishable way. We have those - digits.
Human phonemes exist in a continuous N-dimensional space. There are two problems to defining a universal phonetic set: 1) different populations use different areas of the space. For example, some cultures use hardly any vowels, some hardly any consonants. 2) different populations quantize the space at different boundaries. So even two cultures who both have 5 vowels may find that what is unambiguously 'e' in one culture is 'a' or 'e' in another. And those are just the major problems. The usual solution is to have a set of glyphs that the are labeled in a locally distinguishable way. We have those - digits.