Connecting DECT Phones Through Sound Cards For Asterisk


I couldn’t think of a better title. Here’s how it goes: [onno] wanted to convert a DECT phone for VOIP use. First he tried using transformers for the audio, but was unhappy with the noise and echo. He describes how to do a direct tap like [Christoffer]’s Skype phone, but includes all of the necessary measures to keep from frying your sound card. The main piece of this project is his hacked “chan_oss” driver for Asterisk. Using the driver, Asterisk is able to ring the DECT phone. It also detects whether the phone is off-hook by comparing the sound input to the known line noise level. The phone can dial using DTMF just like any standard phone.

10 thoughts on “Connecting DECT Phones Through Sound Cards For Asterisk

  1. Hi,
    no, I was just not aware of the fact that hackaday has such a big readership. Sorry! The server is connected through a DSL line only. With patience, you should be able to get through. Sorry again!


  2. I love hackaday but the posts are sometimes lacking or just post somthing bland. So, What i have done is made a blog similar to hackaday that you can all check in addition to hackaday. send me links and I’ll post em’too. I just posted the first links including the first psp trojan news and a bunch of other hacks; hardware, os help and other stuff. Let me know what you think. Thanks

    the url is the redirect for it is if your lazy.

  3. I think this project is a good idea, and I plan to try it out for myself.

    However, after messing around with Asterisk in several settings, I have come to the conclusion that telephones based on the desktop computer just don’t cut it because desktop computers are so unreliable. It takes a lot of work to make them as reliable as the analog phone system, from UPS’s on the computer and all network switches to not running windows, and if on linux, making sure that your processor is fast enough that if firefox starts taking up all the memory and CPU the phone conversation doesn’t get all choppy.

    The alternative is to hack together something out of a low-cost board like this one and a cordless phone:

    But with the grandstream 2000 IP phones costing $80, you end up at the same price or more. Which isn’t reason not to do it, in the end you will have more control and features.

    Like I said, I will get around to doing this at some point, but I wouldn’t want to depend on a desktop PC for 911 access.

  4. Hi,
    I didn’t mean that as a replacement for the regular phone (which I have to have anyway – it is bundled with DSL here) and I see the reasons why one wouldn’t trust his/her desktop computer for important calls.. :)

    I’m rather thinking of using it as a second phone to reduce phone costs.

    The problem with choppy sound when starting firefox do not seem to occur here, at least with normal, moderate PC usage.
    Setting asterisk’s nice level below zero helps alot.

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