Speaker symbols are U+1F507-1F05A. Magnifying glass is U+1F50D. There's not really a microphone off/on codepoint, but there is a microphone at U+1F3A4.
You could set up a ccmp feature ligation for /u1F3A4_uni20E0 but note that this may not work because U+1F3A4 is an emoji character so software may fall back to the system emoji font instead of using yours, meaning that the substitution doesn’t happen.
Thank you for your advice John. This font is for a sealed environment with no interaction with any computer or additional fonts (flight deck implementation). The client has previously mapped these glyphs to particular ascii slots. I was thinking that mapping them to proper unicode would be an improvement, but in the end I think not
Comments
Not perfect, but I don’t think it is illegitimate either.
You could set up a ccmp feature ligation for /u1F3A4_uni20E0 but note that this may not work because U+1F3A4 is an emoji character so software may fall back to the system emoji font instead of using yours, meaning that the substitution doesn’t happen.