@GrandDixence Very interesting, I would be happy about a little report

I’ve been fascinated by “building” my own mobile phone network for a long time, but never really had the time to delve further into it

NilsL

My craft project “Own mobile network with srsRAN_4G and LimeSDR-Mini” has come to an abrupt stop. The LimeSDR Mini emits a decent 4G/LTE cellular signal at the upper end of Band 7:

The “manual mobile network search” from the (older) smartphone finds its own mobile network as “22899”:

But logging into this mobile network doesn’t work because I can’t find a way to allow all SIM cards in circulation to log into your own mobile network in the core network (EPC).

The srsEPC program only allows the registration of SIM cards whose data is stored in the user database (srsEPC: user_db.csv). Self-issued SIM cards are required to store the SIM card data. SIM cards suitable for this purpose are available from Sysmocom, for example:

https://www.sysmocom.de/products/sim/

The srsEPC program is part of the open source product srsRAN and provides the core network (EPC) of a 4G/LTE mobile network. Other open source products for operating a core network (EPC) of a 4G/LTE cellular network suffer from the same SIM card problem. For example Open5GS:

https://github.com/open5gs/open5gs/issues/611

My instructions for the craft project:

- Own 4G/LTE mobile network with srsRAN_4G and LimeSDR-Mini on a Raspberry Pi 4 with Ubuntu 20.04 LTS

can be found at:

https://github.com/GrandDixence/CoverageMaps/blob/main/Own_Mobile Network/Installation-Guide_srsRAN_Ubuntu_20.04.m d

My instructions for the craft project:

- Own 2G/GSM mobile network with OsmoCOM and LimeSDR-Mini on a Raspberry Pi 4 with Ubuntu 20.04 LTS

can be found at:

https://github.com/GrandDixence/CoverageMaps/blob/main/Own_Mobile Network/Installation-Guide_OsmoCOM_Ubuntu_20.04.m d

Maybe these instructions will help someone…

@Dolce83

Interesting that Swisscom made this suggestion. 👍

I’m also surprised that this was recommended by Swisscom
@Dolce83

This repeater amplifies signals from all providers. Accordingly, you need permission from all providers.

And for the sake of completeness, it should be mentioned that the responsibility ultimately lies with you. If disruptions occur, you are liable.

The declarations of conformity are missing on the Myamplifiers site, perhaps I overlooked that (CE is not enough).

@Dolce83 @foobar

Even has its own link for Swisscom!

https://www.myamplifiers.com/de-ch-swisscom-signal-boosters/

@WalterB
The site is quite dubious, I doubt that it was created with the consent of the operators.

There are also providers listed that do not have their own network.
The business address is just a trading company with its headquarters in Gibraltar and a mailbox in Munich (86 companies in a small building)

There are also the legal problems that I mentioned. Lack of declaration of conformity and the fact that you need permission from all providers.

“If you import a mobile radio repeater from abroad, you are responsible for its conformity; importing non-conforming radio equipment is a punishable offense.”
[https://www.bakom.admin.ch/bakom/de/home/geraete-anlagen/besondere-geraete/mobilfunk-verstaerker.html](https://www.bakom.admin.ch/bakom/de/ home/devices-systems/special-devices/mobile-radio-amplifiers.html)

@foobar

I am of the opinion that you are not allowed to use the name “Swisscom” if it is dubious because Swisscom would certainly take legal action.

There are also some users who use it with a Swisscom subscription.

Of course I can’t check whether it’s fraud.

You can ask Swisscom whether this is official. I doubt it.

As for cheating… the amplifiers probably already work. It’s just clever marketing and the responsibility ultimately lies with the buyer.

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@Dolce83 wrote:

What I don’t understand is how such a small thing with such a short range can cause a disruption in the Swiss/cantonal/local mobile network (regardless of which provider). And how is OFCOM or Swisscom supposed to find out about this device?

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Normally, interference from such low-power transmitters is not noticeable.

The neighbors may, for example, have poorer reception due to the overlay, but OFCOM will therefore not become active (only if there is specific information).

For example, we once discovered an illegal repeater by chance during maintenance work when the cell was switched off and strong uplink signals to a foreign cell were visible in the spectrum.

As mentioned, this solution was offered to me by Swisscom itself.

I would get this in writing, as would all other providers.
The MA probably just googled it and that was the first hit. They seem to be tops in marketing, not unusual for a shell company.

Everything legal about operating an active signal amplifier for the mobile phone signal (mobile phone repeater) is listed in sufficient detail on the (already known) BAV website:

[https://www.bakom.admin.ch/bakom/de/home/geraete-anlagen/besondere-geraete/mobilfunk-verstaerker.html](https://www.bakom.admin.ch/bakom/de/ home/devices-systems/special-devices/mobile-radio-amplifiers.html)

If the mobile phone provider (e.g. Swisscom) detects a disruption in the downlink or uplink, the network technician who specializes in radio interference is tasked with troubleshooting the problem and visits the faulty mobile phone antenna. If this network technician finds an illegal cell phone repeater as the source of the disruption, OFCOM comes with the police in tow and hands out a hefty fine to the operator of the illegal cell phone repeater.

The video below provides an insight into the everyday work of a network technician at Deutsche Telekom who specializes in radio interference:

https://media.ccc.de/v/35c3-9407-die_verborgene_seite_des_mobilfunks

https://www.youtube.com/watch?v=CSZWTaTu9As

The video deals with the topic of “mobile radio repeaters” starting at 34:36 minutes.

The Swiss counterparts most likely work identically. The legal situation is also identical.