GSM

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Overview

An experimental private GSM network is provided by Osmocom during the Camp.

It is set up by the GSM/MOC (Mobile Operation Center) near Workshop-3. You can use the GSM network to place calls or send SMSs for free on the GSM and DECT networks.

No GPRS for internet or data traffic is provided, as this would quickly lead to congestion with many subscribers on the very limited bandwidth of a few single-TRX GSM BTS.

SIM card, registration

To be able to use the GSM network, you require a SIM card dedicated for the CCC event network.

Any SIM issued at any of the previous CCC events with a GSM network will automatically work.

If you don't have a SIM from a previous event, you can obtain one from the POC (Phone Operation Center). There is only a limited quantity available, so please only buy a new card if you don't have one from previous events.

After you have obtained a suitable SIM,

  1. Register/log-in on eventphone
  2. Register a new extension with phone type "GSM". Give the system a couple of minutes to synchronize with our in-house GSM provider. Relax. Maybe have a nip of your favorite caffeinated beverage.
  3. Dial the GSM token shown in the details view of your extension. This step completes the registration process and pairs your device/SIM with the event's GSM network. If you ever feel like switching devices or SIM cards, then just redial this number on your new device.

Additional information

  • To get your own extension number by dialing *#100#.
  • You can re-use the GSM token you got when creating an extension with any SIM for this network.
  • The MCC (Mobile Country Code) is 262 (Germany), the MNC (Mobile Network Code) is 42.
  • The ARFCNs used are in the upper part of the 1800MHz DCS frequency band (former DECT guard band) and used under License of the German regulatory authority (BNetzA).

Technical Information

sysmoBTS hardware

We use sysmoBTS hardware as actual GSM BTS (Base Transceiver Station). The software on the sysmoBTS is the Free Software program OsmoBTS, developed under the Osmocom umbrella. OsmoBTS implements the GSM protocol layer 2 and interfaces towards OsmoNITB of OpenBSC using the A-bis over IP protocol in a dedicated VLAN of the switched Camp ethernet backbone.

OsmoBTS and OpenBSC software

The Software used for operating the heart of this private GSM network is the OsmoNITB (part of OpenBSC), developed under the Osmocom umbrella project. You can find more information about this at http://openbsc.osmocom.org/. Many developers and contributors of those projects are present at the Camp, you can find us in the Osmocom Village. Feel free to come by and learn more about the world of Open Source Mobile Communications.

If you want to learn more about running your own network with OpenBSC, please consider attending the Runing your own GSM network with OpenBSC OpenBSC workshop at the camp.

Linux Call Router: Interface to POC

In order to interface with the VoIP, wired and DECT network of the POC, we use LCR as a gateway between the OsmoNITB on the GSM side and the Main Switch of the POC.

Related Projects