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There is a DECT network and SIP at MCH2022 operated by the µPOC, additionally there will be a fieldphone network operated by the Chaosvermittlung


You can register your personal DECT extension for GAP-compatible DECT handsets at the µPOC Frontend.

If you have registered your DECT extension ahead of time, skip this next step.


  1. To register your extension go here to signup.
  2. After registering yourself, goto my extensions to register an extension.
  3. When you have done that, then you can self-register your DECT Phone.

Self-register DECT phone

  1. After claiming an extension, click on the green "PIN" button on my extensions page.
  2. Then connect your DECT to any of the base stations (connect handset to base station). If the device asks for a PIN just Use 0000
  3. Finally dial the PIN number on your phone, to bind it to your extension .

Once activated, you can call extensions within the MCH2022 telephony network, but also make free calls to The Netherlands and several other countries in Europe and over the world.

Not sure if your phone is supported? Check the compatibility list.


You can register your personal SIP extension at µPOC Frontend. By clicking on the ℹ️ at your extension, you'll find all needed credentials to connect to our SIP service.

SIP Server:
SIP Port: 5060 (UDP, no TLS)
SIP Username: <your extension>
SIP Password: <your generated password>

Incoming and outgoing calls

  • Outgoing call to The Netherlands:
0 <national number incl. 0>
Netherlands: 085 234 2000 becomes: 0 085 234 2000
  • Outgoing call to a foreign country:
0 00 <country code and number>
Germany: +49 721 266767 2000 becomes: 0 0049 721 266767 2000

You can also be called from the outside world via the following dial-in numbers:

Netherlands: +31 85 234 xxxx
Germany: +49 721 266 767 xxxx

(where xxxx is your personal extension number)


The phonebook can be found here.


Like on earlier hacker events, the Chaosvermittlung is set out to provide a power independent and low-tech phone network.

As some of you might be wondering what the hell is a field phone and why do I want to have one if I already have a SIP/DECT phone. Let us explain a bit more about how these fieldphones work:

  • Field phones are battery powered telephones without a dialing pad connected to a central manual phone exchange.
  • To start your call you have to turn a crank on the side of the phone.
  • An operator will be alerted, answer your call and you can tell him/her which field phone or DECT/SIP number you want to reach.

Now as you know what field phones are you may still be asking yourself: "why do I want to have such a device for my OC or village". As mentioned above the field phones are battery powered and since power cuts can happen, a power independent communication channel is nice to have. Also, because field phones run on their own copper network, their service is not dependant on IP connectivity.


As we have a limited Amount of Ports on our manual exchange (60), wie like to have people telling us if they want to have a fieldphone connected. There for if you want to have a port please use our pretix to "order" one:


We appreciate the tremendous support we get from angels operating the switch board. This keeps the network up and operational! If you are looking for other ways to contribute, please consider recording another voice for the talking clock (details at Send contributed voice recordings to

Further information

  • There is also a sip server besides DECT, which you can use with your favorite sip client. When registering your extension, please choose "SIP Account" as extension type. The server runs at Port 5060 UDP.
  • There is also a good chance to enjoy DECT coverage even at the parking lot.
  • Check the MCH2022 website to see when DECT registration will open.

Behind the scenes

  • Alcatel OmniPCX 4400
    • Multiple chassis from VH to ACT28
    • multiple DECT line cards
    • single mode fibre connection between the different chassis
  • sip uplink kindly provided by speakup.


  • 2x 30 Port Manual exchange
  • 2x 4 Port DECT Uplink