Phone plays message when passcode entered

Hi guys.

I'm hoping for some advice on the feasibility of my project before I try and complete it. I have an old 'modern' rotary phone, like this one ( and I'm hoping I can use it in an escape room.

I'm thinking that when you type in the correct number (password) it will start playing a message through the hand piece speaker that gives a clue.

My current plan is to use a DFplayer to play an mp3 on repeat through the speaker... is this doable or do I need to rethink my hardware?



Simplest way is with a DTMF decoder, it's unlikely that abombination would offer LD dialling. You can inject audio easily via its standard POTS connector.

I once wrote a dtmf (tone dialing) decoder sketch for telephones: (see post #74)
but you can also buy a cheap hardware module to do the same.

You may also find something here. Escape room/Telephone projects seem quite popular here: