Speech recognition of a small set of possible words is basically a solved problem. It's why you've been able to call a phone support line and read numbers to it

Speech recognition of a small set of possible words is basically a solved problem. It's why you've been able to call a phone support line and read numbers to it for years and years now; speech recognition for 10 digits and a handful of control words is basically done. So, if your project can be built on that, good news; you can build now.