I am trying to figure out what kind of microcontroller (or even SBC) to use to make this project a reality.
I was really inclined to base this project around an RN52 bluetooth module, but due to the (relatively) high price, I'm looking for another candidate (maybe an ESP32?)
If you have any ideas, please feel free to leave a comment, I do really appreciate any help :)

The main scope of this proejct is to:

• Be able to use the integrated keypad to input a phone number
• Play a ringtone on the Beocom's loudspeaker
• Be able to answer a phone call by lifting the receiver and to terminate the call by placing it on the holder
• Be able to use the mute key to stop the ringtone (without closing the call) or to mute/unmute the microphone while in a call
• Be able to reject a call by pressing the R button
• Be able to use the integrated linear potentiometer to adjust the ringtone volume
• Be able to redial the last number by tapping the redial button

These are the minimum functionalities I want the replacement PCB to perform to make the project a success.

Other thing that would be nice to implement would be:

• Reproduce the appropriate DTMF tone when pushing a key
• Be able to hear the call via the loudspeaker
• Be able to speak the calling number or contact when receiving a phone call (this would basically require a TTS engine and probabily require a small SBC)
• Respect the "do not disturb mode" of the phone
• Be able to store 3 numbers in memory to speed dial them by using the M1, M2 and M3 keys 9