Telecom Foundations
Path
Path
The essential starting point for telecom security training. Build the architecture, protocol, and identity knowledge required before any specialist track, including 5G security courses and telecom threat modeling.
// OVERVIEW [PATH CONTEXT]
Path Context & Goal
Telecommunications is the backbone of the connected world - from undersea cables carrying 99% of intercontinental data to the cellular towers enabling mobile connectivity. This path provides the **essential engineering foundation** and **telecom security training** required before any security specialization. You will learn how signals propagate, how networks are built, how calls are routed, and how the global numbering system identifies every device on the planet. Whether you are looking for a **hands-on 5G security course** or **telecom signaling security** expertise, every concept is mapped to its modern **3GPP Release 18/19** evolution, ensuring you understand both the legacy infrastructure you will audit and the 5G-Advanced systems being deployed today.
// THE CURRICULUM [LEARNING OBJECTIVES]
Network Architecture
Describe the access, transport, and core layers of fixed and mobile networks - and identify where each attack surface lives.
Signal Theory
Explain analog-to-digital conversion (PCM/Nyquist), modulation schemes, and why SIGINT starts at the physical layer.
Switching & Transport
Compare circuit-switched TDM with packet-switched MPLS and trace a voice call through E1/SDH/DWDM hierarchies.
Identity Systems
Decode IMSI, MSISDN, IMEI, and TMSI structures - and explain how each can be abused for tracking or interception.
Signaling Protocols
Map SS7, SIGTRAN, SIP, and Diameter to their OSI layers and security implications.
Mobile Generations
Trace the architectural evolution from 2G NSS to 5G SBA - explaining what changed, what was inherited, and what was fixed.
Subscriber Management
Explain SIM/USIM/eSIM architecture, the AuC challenge-response flow, and HLR/HSS/UDM database roles.
Security Mindset
Identify the three primary telecom attack surfaces (access, interconnect, OAM) and the specialized defenses that protect them.
PSTN Hierarchy
Map the Class 1–5 switching hierarchy and identify the security boundary at each tier - from international gateway to local loop.
Digital Transmission
Trace the PCM digitization chain and understand T1/E1 frame structure, DS0 multiplexing, and ISDN BRI/PRI interfaces.
PSTN Signaling
Decode ISUP IAM/ACM/ANM/REL flows and distinguish CAS robbed-bit signaling from CCS architecture.
GSM Architecture
Map the complete BSS/NSS stack - BTS, BSC, MSC, HLR, VLR - and their security boundaries.
A5 Ciphering
Analyze A5/0, A5/1, A5/2, and A5/3 cipher properties and known cryptographic weaknesses.
GSM Attacks
Operate IMSI catchers, downgrade attacks, and passive intercept techniques used against 2G networks.
GPRS Security
Understand GPRS packet-switched architecture, SGSN/GGSN roles, and GTP tunnel exposure.