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GSM Mobile Networks SDM Software

USSD Gateway with Osmocom

Unstructured Supplementary Service Data or “USSD” is the stack used in Cellular Networks to offer interactive text based menus and systems to Subscribers. If you remember topping up your mobile phone credit via a text menu on your flip phone, there’s a good chance that was USSD*. For a period, USSD Services provided Sporting Scores, […]

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GSM Mobile Networks

GSM with Osmocom: OsmoSGSN for Packet Data

Configuring the Osmocom Serving Gateway Support Node (SGSN) for 2G/3G networks.

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GSM Mobile Networks RF

GSM with Osmocom: Handovers

A look at the Handover process between Cells / BTSs in GSM using the Osmocom stack.

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GSM Mobile Networks RF

GSM with Osmocom: Channel Types

When setting up the timeslots on the TRX for each BTS on your BSC, you’ll notice you have to set a channel type. So what do these acronyms mean, and how do they affect the performance of the network? GSM channels break down into one of to categories, control channels – used for signalling, and […]

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GSM Mobile Networks

GSM with Osmocom: Silent SMS & Silent Calls

Depending on if you’re wearing a tin foil hat or not, silent SMS and silent calls could be a useful tool to for administering the network or a backdoor put in to track citizenry! Regardless of it’s reasons for existence, let’s take a look at what it actually does, and how we can use it. […]

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GSM Mobile Networks RF

GSM with Osmocom: GPRS & Packet Data

So far we’ve focused on building a plain “2G” (voice and SMS only) network, which was all consumers expected twenty years ago. As the number of users accessing the internet through DSL, Dial Up & ISDN grew, the idea of getting this data “on the go” became more appealing. TCP/IP was becoming the dominant standard […]

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GSM Mobile Networks

GSM with Osmocom: SS7 & Sigtran

SS7 Basics and Osmo-STP as a Signaling Transfer Point

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GSM Mobile Networks

GSM with Osmocom: NanoBTS

Setting up ipaccess NanoBTS on Osmocom’s OsmoBSC

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GSM IMS / VoLTE Mobile Networks Voice over IP

GSM with Osmocom: Call routing in GSM

How call routing in GSM works and it’s application in the Osmocom suite

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GSM IMS / VoLTE Mobile Networks RF

GSM with Osmocom Part 9: Calls & SMS at last!

So now we’ve covered the basics of what’s involved let’s get some traffic on our network. For starters we’ll need to start each of our network elements and bring up whichever BTS hardware we’re using. In order for our calls to have audio, we’ll need to set a parameter on the Media Gateway. We’ll cover […]

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GSM Mobile Networks

GSM with Osmocom Part 8: The Mobile Switching Center

Setting up the Mobile Switching Centre for a GSM network using OsmoMSC.

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GSM Mobile Networks SDM

GSM with Osmocom Part 7: The HLR – Home Location Register (and Friends)

What the Home Location Register (HLR) does in GSM, how to set it up and configure subscribers.

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GSM Mobile Networks

GSM with Osmocom Part 6: Integrating our LimeSDR BTS with OsmoBSC

Connecting our LimeSDR based GSM BTS with OsmoBSC.

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GSM Mobile Networks

GSM with Osmocom Part 5: Software BTS with LimeSDR & osmo-bts-trx

Using a LimeSDR as a GSM BTS with Osmocom.

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GSM Mobile Networks

GSM with Osmocom Part 4: The Base Station Controller (BSC)

Configuring a GSM Base Station Controller with Osmocom stack.

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GSM Mobile Networks

GSM with Osmocom Part 3: Introduction to Osmo Software & Virtual BTS

Setting up a virtual BTS in our BSC with Osmocom.

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GSM Mobile Networks

GSM with Osmocom Part 2: BTS Basics

What’s a BTS and where do they fit into the GSM Network architecture?

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GSM Mobile Networks

GSM with Osmocom Part 1: Intro

Intro to our post series on GSM using the Osmocom stack,

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Mobile Networks RFCs & Standards Voice over IP

Demystifying SS7 & Sigtran – Part 3 – SS7 Lab in GNS3

Setting up our GNS3 environment with a bunch of SS7 Nodes

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Mobile Networks Security SIM Cards

SIM Card Sniffing with Wireshark

Using Wireshark to sniff communication between your computer and Smart Card / SIM Card