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Is there an analog connector for Raspberry PI

Former Member

I want to connect a Respberry PI to an analog phone line to detect incoming calls and detect caller number.  Is such an add-on available?  Possibly would need two ports: one would be phone and the other into netowrk provider line port.

  • You might be able to get this capability with a USB modem.  The analog circuits needed to do this are all there, but who knows if the modem implements the features and whether there's a driver that can access it.

  • in reply to johnbeetem

    If you can find one, an old style modem with an RS232 port may be a better bet as there's no real need for any sort of drivers and you're at far less risk of it being one of those weird everything-in-software winmodems.

    It's been many years since I bought an analogue/rs232 modem, but I remember them being very cheap by that point - 7 or 8 quid IIRC.

     

    The other ways to do it would be an FXO device meant for Asterisk, possibly something like http://sangoma.com/products/telecom_boards/analog/usbfxo.html for usb or something like the Cisco SPA orGrandstream handytone for ethernet. Unfortunately lots of these things want to do more and cost many times what the Pi does image

  • in reply to Former Member

    selsinork wrote:

     

    If you can find one, an old style modem with an RS232 port may be a better bet as there's no real need for any sort of drivers and you're at far less risk of it being one of those weird everything-in-software winmodems.

    It's been many years since I bought an analogue/rs232 modem, but I remember them being very cheap by that point - 7 or 8 quid IIRC.

    It may be hard to find an old-style modem that supports caller ID, so check specs carefully.  There are also modem modules available based on Silicon Labs DAA (Data Access Arrangement) chips.  See http://www.silabs.com/products/modems/Pages/Modules.aspx.  Cheapest one I found was US$49.50, with UART interface.  I did a little searching and found that Maxim now has DAA and low-speed modem chips: http://para.maxim-ic.com/en/search.mvp?fam=fxo_modem&tree=te_products, from Teridian Semiconductor Corporation.  There may be some inexpensive modules based on these.

     

    As you look at these chips and their application notes, you'll notice that hooking up to telephone lines is actually pretty nasty.  Off-hook and ringer voltages are painful.  You'll need good isolation from your RapPi circuitry.