Categories
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. […]

Categories
EPC EUTRAN LTE Mobile Networks

S1AP – Relative Capacity (87) on MME

Functionality of eNB MME selection based on Relative Capacity IE

Categories
EUTRAN LTE Mobile Networks

Viewing the SIB – The LTE System Information Block with SDRs

Using SDR hardware to view the LTE System Information Block’s contents.

Categories
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 […]

Categories
GSM Mobile Networks

GSM with Osmocom: SS7 & Sigtran

SS7 Basics and Osmo-STP as a Signaling Transfer Point

Categories
Voice over IP

FreeSWITCH + ESL = Programmable Voice

An overview of FreeSWITCH’s ESL

Categories
EPC LTE Mobile Networks

Open5GS EPC: SGW selection by eNodeB ID / TAC

Using the new functionality in Open5Gs to select S-GW based on TAC or eNB ID.

Categories
EUTRAN LTE Mobile Networks RFCs & Standards Software

Diameter Droplets – Origin-State-Id AVP

What the Origin-State-Id AVP does and how it is used to track if a Diameter peer restarts.

Categories
EPC EUTRAN LTE Mobile Networks

BaiCells USIM PLMN Issues (MNC 314 / MCC 030 vs MNC 311 / MCC 98)

Why the BaiCells PLMN changes?

Categories
Kamailio Voice over IP

Kamailio Bytes – UAC – Authenticate Outbound Calls

Using UAC module to authenticate outbound calls where you need to respond to a 401 Unauthorised Response, or a 407 Proxy Authentication required

Categories
RF

Dumb Lesson in RF Connectors

Learning a very dumb lesson in antenna selection.

Categories
EPC EUTRAN LTE Mobile Networks RFCs & Standards

LTE UE Attach Procedures in Evolved Packet Core (EPC)

A look into the signalling messages between Network elements in an Evolved Packet Core exchanged during the Attach Procedure

Categories
EUTRAN LTE Mobile Networks RFCs & Standards Voice over IP

Diameter and SIP: Registration-Termination-Request / Answer

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 […]

Categories
EPC LTE Mobile Networks RFCs & Standards Voice over IP

Diameter and SIP: User-Authorization-Request/Answer

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.

Categories
EPC LTE Mobile Networks RFCs & Standards Voice over IP

Diameter and SIP: Server-Assignment-Request/Answer

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. […]

Categories
EPC LTE Mobile Networks RFCs & Standards Voice over IP

Diameter and SIP: Location-Info-Request / Answer

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 […]

Categories
EPC LTE Mobile Networks RFCs & Standards

Diameter and SIP: Multimedia-Authentication-Request/Answer

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 […]

Categories
EPC LTE Mobile Networks

Connecting any 3rd Party HSS to Open5GS MME

Connecting an external / 3rd party HSS to Open5GS

Categories
GSM Mobile Networks

GSM with Osmocom: NanoBTS

Setting up ipaccess NanoBTS on Osmocom’s OsmoBSC

Categories
EUTRAN LTE Mobile Networks

srsLTE Install for BladeRF & LimeSDR on Debian / Ubuntu

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 […]