March 2026 - OpenBSC - lists.osmocom.org

On the use of 'decmatch' in TTCN-3
by Harald Welte 31 Aug '26

31 Aug '26

Hi, I know that TTCN-3 is still new to a lot of you, but we are writing tons of integration testing against the various osmocom programs in it. It is quite amazing technology, and I would like to ask you to bear with me reading this mail :) Pau was stating the question earlier today on not finding an example on how to use decmatch. Indeed, it took me some months to find that gem in the TTCN-3 world. It solves the problem that you often have during test of layered protocol stacks: you have separate encoders/decoders for each protocol layer, and now you want to match on some of the *inner* payload. So normally, you have some kind of header definition + a binary (octetstring) payload. This happens in RSL with the L3_INFO IE, and just the same on BSSAP/DTAP where again the L3 message (for example call control) is encapsulated inside one information element. Now you have multiple options of addressing the problem: a) hand-written calls to the decoder function b) write na 'emulation' for the entire protocol layer c) use decmatch. a) would look like this (pseudo-code): var octetstring l3oct; var RSL_Message rsl RSL.receive(tr_RSL_DATA_REQ(g_chan_nr, ?, ?)) -> value rsl { var PDU_ML3_MS_NW l3 := dec_PDU_ML3_MS_NW(rsl.payload); if (match(l3, some_template)) { ... do something } ... } Which uses the built-in pattern-matching on the RSL port to match any message that matches the tr_RSL_DATA_REQ template, and stores the resulting RSL message in a variable. It then uses an explicit call to the decoder function of the L3 message, and then uses regular conditional expressions for further matching on that inner L3 payload. This is more or less how you would write in C, python or any other quite imperative programming languages. It's very verbose, time consuming and un-abstract/elegant. TTCN-3 has many declarative aspects to it. Code like the above is a waste of your time :) b) would mean that you implement some test component that handles the RSL messages on its bottom side test port, and the L3 messages on its top side test port. That is a possible way, and if you need a lot of state/logic of RSL, it maeks sense. But what if you really simply want to have a match? Then it would be a lot of effort and a large detour. c) decmatch to the rescue! You can write RSL.receive(tr_RSL_DATA_REQ(g_chan_nr, ?, decmatch tr_RRM_RR_STATUS)) which means: * do a receive on the RSL test port, and match on an incoming RSL message that matches the tr_RSL_DATA_REQ template, with channel number specified, link_id any (?), *and* if the octetstring payload, if decoded, matches the template tr_RRM_RR_STATUS ! This is *extremely* powerful and expressive. It allows you to condense complex, parametric template matching over multiple proocol layers. It would in the end match RSL DATA REQUEST, only if they contained a [valid] encoded RR STATUS. See https://gerrit.osmocom.org/6229 for the actual test case I used for the above examples. Please also note that I never had to even write the function name of the decoder (dec_PDU_ML3_MS_NW), but TTCN-3 *automatically* figures out which decoder function it must call in order to decode from the binary octetstring. Happy (TTCN-3) hacking + Osmocom bugfixing, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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E1 to IP with iCE40 E1 USB interface
by Alina Androne 28 May '26

28 May '26

Hello, How can I utilize the iCE40 E1 USB adapter to transition from E1 to IP in a GSM network, connecting a physical Siemens BSC (which has a BTS connected) to OsmoMSC? Only the BTS and BSC are physical. I already have osmo-e1d installed. Should I use osmo-e1d or dahdi version for this transition? What would be the best approach to begin the process? Regards, Alina

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GSM Silent call
by samir 04 May '26

04 May '26

Hi, I have read that silent-calls in GSM can be used to make a call to a target MS and listen to it without having the target knowing it. Is this theoretically possible ? If yes, can it be done in OpenBSC ?

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cmd2 update causing pySim-shell to fail
by bryan coxwell 02 May '26

02 May '26

Hi all, Just wanted to share an issue and a quick workaround I found for it in case anyone else has the same problem. I believe a cmd2 update is causing pySim-shell to fail. After installing it on a fresh install of Ubuntu Server 20.04 and getting the following error when I run "python3 pySim-shell -p0": >Using PC/SC reader interface >Autodetected card type: sysmoUSIM-SJS1 >AIDs on card: > USIM: a0000000871002ffffffff8907090000 >Traceback (most recent call last): > File "pySim-shell.py", line 512, in <module> > app = PysimApp(card, rs, opts.script) > File "pySim-shell.py", line 59, in __init__ > super().__init__(persistent_history_file='~/.pysim_shell_history', allow_cli_args=False, use_ipython=True, auto_load_commands=False, command_sets=basic_commands, >startup_script=script) >TypeError: __init__() got an unexpected keyword argument 'use_ipython' If you run into this you can fix it by uninstalling cmd2 and reinstalling cmd2 with "pip3 install cmd2==1.5". Best, Bryan

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Re: AMR on E1 BTS with tw-e1abis-mgw
by Sipos Csaba 30 Apr '26

30 Apr '26

Hi Mychaela, The AMR capability works great with your drop-in MGW implementation, voice quality improved a lot. I also tested the FR/EFR part earlier, which also works as expected. CSD is definitely interesting, once I have at least two CSD capable devices, I will give that a try as well. We already tried with a Nokia MetroSite, and early next year I am planning to try with our UltraSite setup at the museum as well. Would be nice to be able to send fax on top of GSM :-) The OML dialect we have in Osmocom now (called "nokia_site") despite its name it supports old Nokia equipment up to Felxi EDGE, Multiradio and Multiradio10 (on E1), if anyone else is interested, so OML support is not limited to just the Nokia *Site family. Some of this stuff is still running in less fortunate countries... Little bit of tweaking will likely needed, but at least it is not a completely unknown part like AoIP. Regards, Csaba

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SMS: UCS-2 concatenation with UTF16 emoticons
by Keith 26 Apr '26

26 Apr '26

Hi all, I noticed that SMS with emoticons on the boundary of the concatenated segments are not displaying correctly on the destination handset. * - imagine the disaster when that kiss-blowing smiley face thing at the end of your SMS turns out as a diamond with a ? for the recpipient! OMG, the potential butterfly effect is too much to think about... :)) So... This is my analysis: We have 140 bytes for the message, less the 6 bytes for the user header data in the case of concatenated SMS , leaving 134 bytes. It's well know that this means 67 characters per segment for an SMS using UCS-2 encoding. But, it we fill the message with emoticons that are using 4 bytes per 'character', then we have space for 134/4 = 33 and a half. Ooops. Still, the destination handset should reassemble the message and stick the two "halves" of the emoticon together, right? - except I'm not observing this. To rule out us doing something wrong in osmo, I wonder might somebody else (who has an unlimited SMS package) from a commercial provider try sending some crafted SM from one emoji-enabled phone to another, something like this: 😱abcdefghijklmnopqrstuvwxyz123456789abcdefghijklmnopqrstuvwxyz123😱56789 That's likely going to get mangled by mailing list or your mua, so it is: [4 byte emoji]abcdefghijklmnopqrstuvwxyz123456789abcdefghijklmnopqrstuvwxyz123[4 byte emoji]56789 You could also try various messages filled with emojis. Of course, if you bring up your osmo network with SMPP-mirror you can watch the trace in wireshark, you'll see when the last emoji gets chopped in two. You could try the same message on osmo and your commerical network. If it's actually a problem of the phones, you should get [4 byte emoji]abcdefghijklmnopqrstuvwxyz123456789abcdefghijklmnopqrstuvwxyz123[two diamonds with ?]56789 Thanks! Keith.

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Front and back sides of an MSC
by Mychaela Falconia 26 Apr '26

26 Apr '26

Hello Osmocom community, I have a question about terminology that is not really specific to Osmocom, but is specific to GSM/3G/etc cellular industry, or whatever is left of it. An MSC in a GSM or 3G or any other circuit-switched cellular network has two sides: one side facing the RAN (A interface in GSM, IuCS in 3G), the other side facing PSTN or ISDN or BICC or SIP-I or whatever the fixed telephone network may be. My question: is there a general industry-wide agreement as to which side should be called the front and which should be called the back? To me it seems intuitive to refer to the A/IuCS side of an MSC as the front and the PSTN/ISDN/BICC/SIP-I side of the same MSC as the back. However, I am just one person, and I have no idea whether or not my view is intuitive to others. And it would even worse if the opposite convention happens to be widely used... Hence I am asking this community, in the hope that someone with more industry experience would know how telco network engineers casually refer to RAN-facing and fixed-network-facing sides of an MSC. For a long time I had the idea of building ThemWi MSC as a modular system (multiple processes talking to each other via sockets) with a stripped-down OsmoMSC derivative as the "central" component, and with a radically different placement of MSC-MGW. However, as I started working on more detailed design, I realized a major flaw in my originally envisioned architecture: my original approach to MSC-MGW would break TFO for AMR, specifically the dialogue between TFO-aware BTS and the TRAU equivalent in the MGW. I am now spinning a new architecture in my head, one which tentatively includes two dissimilar MGWs in the MSC. If my front vs back terminology is valid, then the front MGW (talking to AoIP user plane) would perform speech transcoding but become a transparent pass-through for CSD (basically a software-only, IP-based equivalent of a hardware TCSM colocated at the MSC site), while the back MGW would be a transparent pass-through for speech calls, but turn into a complex IWF for CSD. This tentative architecture exactly matches the placement of speech transcoding and CSD IWF functions in traditional hardware MSCs of TDM-based, before-AoIP world. But I need to know if I should keep these front and back terms, or swap them the other way around. M~

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21 Apr '26

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ip.access nano 3G S8 Configuration
by John Thewlis - Meath Broadband 20 Apr '26

20 Apr '26

We are trying to setup this AP as part of the 3.5G Osmocom project. We have the software stack operational and are now preparing the nano for testing. When we try to login via telnet at port 8090 we are getting a constant refusal to connect:- root@osm/openbsc/openbsc/src/ipaccess# telnet 192.168.192.30 8090 Trying 192.168.192.30... telnet: Unable to connect to remote host: Connection refused The device seems to be locked as indicated by the leds on the front panel. We have tried resetting the nano to see if this would help but to no avail. Any ideas as to how to access the device for initial configuration?. Thanks John

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Need nano3G (S8 - Model 237A)
by Akib Sayyed 16 Apr '26

16 Apr '26

Dear List I am extremely sorry for off the topic question. I am willing to buy nano3G Nodeb. Is anyone in list have spare which can be sold. Please let me know. -- Akib Sayyed Matrix-Shell akibsayyed(a)gmail.com akibsayyed(a)matrixshell.com Mob:- +91-966-514-2243 <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

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