Looking for advice on a fairly straight-forward project

Hi folks,

Thanks for checking out my post. Let me start off with a serious newbie alert. The world of micro controllers is very new to me, but I do have a technical software background, including programming.

I believe my project is very straight-forward, but I don't know where to begin, other than I'll need an Arduino board of some variety. The project is for my wife's business.

The idea is she has a digital land-line phone. We need to reconfigure it so that someone will punch in a 4-digit code on the phone's keypad. If they punch in the correct code, the phone will play back a pre-recorded audio file that is heard through the handset. There will only be one correct numeric code out of the thousand possibilities. There will also only be one recorded message. Caveat to this: she may decide she wants one message for the correct code and one different message for all the incorrect responses. The message will be roughly 20 seconds in length.

In short, digital input will be received from the phone's keypad; audio output will be directed to the handset's earpiece.

Any and all advice gladly welcome.


There will only be one correct numeric code out of the thousand possibilities

Ten thousand possibilities.

The idea is she has a digital land-line phone. We need to reconfigure it

And this device is capable of reconfiguration in the manner you require?
You have the manual?

Just a couple questions to better understand exactly what you are attempting to do.

  1. Is this a live phone line, meaning that it is attached to the phone company at the same time it is attached to the Arduino? Or are you using a phone which is no longer used?

  2. If the phone really is attached to the phone company, are you using the keypad of the phone you are attached to or do you want to detect buttons pressed by the calling person?

Does it need to connect to the landline? Or can it be wired into the phones keypad?

And if it needs to be connected to the landline, how do you want to prevent the 4 digits to be dialed for real as well?

If you want to connect it to the keypad it's not that hard indeed. Just wire the keypad to the Arduino, and grab one of those cheap SD voice modules (WT588D-16p for example) and an amplifier (for example PAM8403). Just watch the keys for the right sequence (done a million times before here, just Google), and play one of the two soundtracks when entered.

[EDIT] Ahhh, or do you want it to answer the phone for you?

Thanks for the quick responses.

My bad, there are indeed 10,000 possible entries.

This is not a live phone line. It is not connected to anything other than the Arduino. The phone is like a big box. The Arduino will be embedded inside the phone, so it will be easy to connect the phone's keypad to the Arduino. It seems like the tricky part will be directing the audio output back through the handset. In other words, the end-user will pick up the receiver and punch his code into the phones keypad. the keypad is on the phone's base. The user will then hear the audio output through the handset, not a loudspeaker connected to the Arduino.

Which Arduino board am I looking at for this? I assume I'll also be writing some C/C++ code for this as well, correct?

Thanks again.

That is the most simple for of the project you can have (based on the multiple possibilities from your opening post).

Then it's just like I said. Wire the hook switch and the keypad to the Arduino (just Google that). Use a voice module for the audio and just connect the output (maybe via a amplifier, don't know how powerful the output of a voice module is, might even drive a small speaker directly) to the headset. You just have to open everything up to check the wiring :slight_smile: