LTE

3GPP Long Term Evolution (4G)

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

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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 […]

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Diameter-User-Authorization-Request-Command-Code-300-Packet-Capture
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.

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Diameter - Server Assignment Answer - All
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. […]

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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 […]

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Screenshot of packet capture of Diameter Multimedia-Auth-Request (Diameter Command Code 303) used for IMS authentication
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 […]

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iPhone connecting to SRS LTE eNodeB SDR
EUTRAN
LTE
Mobile Networks

srsLTE Install for BladeRF & LimeSDR on Debian / Ubuntu

Note: I’m running 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 be […]

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EPC
EUTRAN
GSM
LTE
Mobile Networks

OsmoMSC and Open5GS MME – SGs Interface for CSCF / InterRAT Handover

Looking into the SGi interface for Circuit Switched Fallback in LTE to use GSM/UMTS networks for Calls & SMS

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Decoding MAC LTE Frames in Wireshark
EUTRAN
LTE
Mobile Networks

Working with LTE MAC traces in Wireshark

Using Wireshark to view and analyze MAC layer LTE traffic

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EUTRAN
LTE
RF

Field Test on an iPhone

Accessing the Field Testing suite on an iOS Device

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EPC
Kamailio
LTE
Software
Voice over IP

Kamailio Proxy-CSCF Pull

My first Pull / Merge in the Kamailio project was to fix the IMS P-CSCF config

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EPC
LTE
Mobile Networks
Python

Open5GS Python Library / API

A while ago I wrote a Python library for interfacing Open5GS HSS to Python. The Open5GS HSS uses a MongoDB backend, so the library is just running formatted Mongo queries. You can create, edit and delete subscribers in the HSS, along with modifying any parameters you can from the WebUI. Take a look: https://github.com/open5gs/open5gs/tree/master/misc/db/python

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EPC
EUTRAN
LTE
Mobile Networks

Multi Operator Core-Networks (MOCN) for RAN Sharing

Multi-tenancy on the RAN side of the network, allowing an eNB to broadcast multiple PLMN IDs (MCC/MNC) in the System Information Block (SIB).

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EPC
LTE
Python
RFCs & Standards

GTPv2 – F-TIED Interface Types

A quick look at the Interface Types in the F-TIED field in GTPv2

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