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. […]
Functionality of eNB MME selection based on Relative Capacity IE
Using SDR hardware to view the LTE System Information Block’s contents.
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 […]
SS7 Basics and Osmo-STP as a Signaling Transfer Point
Using the new functionality in Open5Gs to select S-GW based on TAC or eNB ID.
What the Origin-State-Id AVP does and how it is used to track if a Diameter peer restarts.
Why the BaiCells PLMN changes?
A look into the signalling messages between Network elements in an Evolved Packet Core exchanged during the Attach Procedure
These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Registration-Termination Request / Answer allow a Diameter Client (S-CSCF) to indicate to the HSS (Diameter Server) that it is no longer serving that user and the registration has […]
The Diameter User-Authorization-Request and User-Authorization-Answer commands are used as the first line of authorization of a user and to determine which Serving-CSCF to forward a request to.
These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Server-Assignment-Request/Answer commands are used so a SIP Server can indicate to a Diameter server that it is serving a subscriber and pull the profile information of the subscriber. […]
These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Location-Information-Request/Answer commands are used so a SIP Server query a Diameter to find which P-CSCF a Subscriber is being served by Basics: The RFC’s definition is actually pretty […]
These posts focus on the use of Diameter and SIP in an IMS / VoLTE context, however these practices can be equally applied to other networks. The Multimedia-Authentication-Request/Answer commands are used to Authenticate subscribers / UAs using a variety of mechanisms such as straight MD5 and AKAv1-MD5. Basics: When a SIP Server (S-CSCF) receives a […]
Connecting an external / 3rd party HSS to Open5GS
Setting up ipaccess NanoBTS on Osmocom’s OsmoBSC
Note: I’m running version 19.12.0 which I installed from the repos due to issues with 20.4.0 (latest when I wrote this) and stability on LimeSDR. I wrote the other day about installing SRS LTE stack, But installing it is one thing, meeting all the requirements to use it with your SDR hardware turns out to […]
Sending SMS over LTE using OsmoMSC and OsmoHLR and the SGs interface for SMSoS
Looking into the SGi interface for Circuit Switched Fallback in LTE to use GSM/UMTS networks for Calls & SMS
How call routing in GSM works and it’s application in the Osmocom suite