I'm trying to build an IVR system using Raspberry Pi. See following diagram

enter image description here

I'm not sure which hardware to use for blue and green boxes.

For the blue box maximum number of phones will be 3. They are just normal phones not IP phones. It should work on both ways.

When dialing into the phone number it will play a message and based on user selection (ivr) call will forward to a one of the connected telephones. If user pressed 1 call will goto only "Telephone 1" ect.

Also when someone dialed from "Telephone 1" it should go thru raspberry pi as a normal call.

Can someone suggest hardware (adapter?) to archive this.

Thank you!


1 Answer 1


At first, it's not a good idea to put the provider link to an unofficial device. They've been checking the current that phones are using and it's easy to figure out you are using an unauthorized or an unofficial device then you may be warned by them.

However, to solve this problem, you should put the provider link to a phone and get an output link from the phone.

I'm not sure which hardware to use for blue and green boxes.

It's possible to make it happened by an "RS232 56K Modem Modules". You just need to find one that could connect to the RPi by USB port like THIS.
You have to manage four USB input by your purpose.

Also, I think you can do it without a "Modulator/Demodulator" modem.

In addition,This link would be helpful.

  • By mistake, I lost 100 reputation for setting bounty for this post. It was my question too and I've searched a lot then find these findings. If it could, upvote.
    – M. Rostami
    Dec 29, 2019 at 20:23
  • Unless someone provides an answer that gets more score I think you will get the bounty in the end.
    – goldilocks
    Dec 30, 2019 at 18:20
  • @goldilocks I asked a question, unfortunately, it's impossible. meta.stackexchange.com/questions/341246/…
    – M. Rostami
    Dec 30, 2019 at 18:23

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