Everything in this guide can be traced to public standards and industry documents. Spec numbers are stable; always open the latest version in the official portal because releases are updated.
1. Standards bodies and portals
| Body | What it publishes | Where |
|---|---|---|
| 3GPP | GSM, UMTS, LTE, 5G specifications (TS/TR, by Release) | 3gpp.org/specifications-technologies |
| ETSI | European standards, also re-publishes 3GPP specs; lawful interception | etsi.org |
| ITU-T / ITU-R | SS7 (Q-series), numbering (E-series), spectrum and IMT definitions | itu.int |
| IETF | Internet protocols (SIP, Diameter, SCTP, HTTP/2, TLS) | ietf.org · rfc-editor.org |
| GSMA | Operator guidelines (FS, IR, NG, SGP documents), roaming, security | gsma.com |
| O-RAN Alliance | Open RAN architecture and interfaces | o-ran.org |
| IEEE | Wi-Fi (802.11), Ethernet (802.3), PTP (1588) | ieee.org |
| SMPP Developers Forum | SMPP v3.4 specification | smpp.org |
| Regulators | Spectrum, numbering, portability | hakom.hr (Croatia) · berec.europa.eu (EU) · cept.org/ecc · fcc.gov (US) |
2. 3GPP specifications used in this guide
| Topic | Specification |
|---|---|
| Network architecture (2G/3G) | TS 23.002 |
| Numbering, addressing and identification (IMSI, MSISDN, GT, GUTI…) | TS 23.003 |
| Basic call handling | TS 23.018 |
| Location management (HLR/VLR procedures) | TS 23.012 |
| SMS technical realization | TS 23.040 |
| SMS alphabets and language | TS 23.038 |
| SMS point-to-point NAS support | TS 24.011 |
| MAP protocol | TS 29.002 |
| Mobile radio interface Layer 3 (2G/3G NAS) | TS 24.008 |
| GPRS architecture | TS 23.060 |
| GTP (v1) | TS 29.060 |
| UTRAN overall description | TS 25.401 |
| 3G security | TS 33.102 |
| E-UTRA/LTE overall description | TS 36.300 |
| EPC architecture | TS 23.401 |
| EPS NAS | TS 24.301 |
| GTPv2-C | TS 29.274 · GTP-U: TS 29.281 |
| S6a/S6d Diameter | TS 29.272 |
| Policy and Charging Control | TS 23.203 · Gx TS 29.212 · Rx TS 29.214 |
| Charging architecture | TS 32.240 |
| LTE security | TS 33.401 |
| CSFB | TS 23.272 |
| SRVCC | TS 23.216 |
| IMS architecture | TS 23.228 · SIP/SDP profile TS 24.229 |
| NR overall description | TS 38.300 · NG-RAN architecture TS 38.401 |
| 5G system architecture | TS 23.501 · procedures TS 23.502 · policy TS 23.503 |
| 5G NAS | TS 24.501 |
| 5G PFCP (N4) | TS 29.244 |
| 5G service-based interfaces | TS 29.500 (SBI technical realization), 29.510 (NRF), 29.518 (AMF) |
| 5G security | TS 33.501 |
| IoT service exposure | TS 23.682 |
| Study into routeing of MT-SMs via the HPLMN (SMS home routing) | TR 23.840 |
3. ITU-T recommendations
- Q.700-series — Signalling System No. 7 (MTP: Q.701–Q.707, SCCP Q.711–Q.716, TCAP Q.771–Q.775, ISUP Q.761–Q.764).
- Q.850 — Cause codes used in call release.
- E.164 — International numbering plan; E.212 — IMSI numbering; E.214 — mobile global titles; E.118 — ICCID.
- ITU-R M.2083 — IMT-2020 (5G) vision; ITU-R M.2150 — IMT-2020 specifications.
4. IETF RFCs
- RFC 3261 SIP · RFC 4566 SDP · RFC 3550 RTP/RTCP · RFC 3711 SRTP
- RFC 6733 Diameter base protocol · RFC 4960 SCTP · RFC 4666 M3UA
- RFC 9113 HTTP/2 · RFC 8446 TLS 1.3
- RFC 8224 / 8225 / 8226 STIR (Authenticated identity in SIP)
5. GSMA documents
| Document | Subject |
|---|---|
| FS.07 | SS7 and SIGTRAN network security |
| FS.11 | SS7 interconnect security monitoring and firewall guidelines |
| FS.19 | Diameter interconnect security |
| FS.20 | GTP security |
| FS.21 | Interconnect signalling security recommendations (master document) |
| FS.52 | Global Title and Diameter End Point Address Leasing Code of Conduct (v2.0; v1.0 covered GTs only) |
| IR.21 | Roaming data exchange (network parameters) |
| IR.88 | LTE and EPC roaming guidelines |
| IR.92 | IMS profile for voice and SMS (VoLTE) |
| SGP.22 / SGP.02 | eSIM remote provisioning — consumer / M2M |
| TADIG documents | TAP3 and RAP roaming billing exchange formats |
| NG.116 | Generic network slice template |
6. Books
- Martin Sauter — From GSM to LTE-Advanced Pro and 5G (Wiley)
- Harri Holma, Antti Toskala — LTE for UMTS and WCDMA for UMTS (Wiley)
- Erik Dahlman, Stefan Parkvall, Johan Sköld — 5G NR: The Next Generation Wireless Access Technology (Academic Press)
- Miikka Poikselkä, Georg Mayer — The IMS: IP Multimedia Concepts and Services (Wiley)
- Travis Russell — Signaling System #7 (McGraw-Hill)
- Jyrki Penttinen — The Telecommunications Handbook (Wiley)
- Jonathan Rodriguez (ed.) — Fundamentals of 5G Mobile Networks (Wiley)
7. Research, incidents and security reports
- Tobias Engel — SS7: Locate. Track. Manipulate. (31C3, 2014) and Karsten Nohl — Mobile self-defense (31C3, 2014): public demonstrations of SS7 tracking and interception.
- Cellusys — IMSI-disclosure research on SMS routing (2016).
- AdaptiveMobile Security — Simjacker (2019).
- Reports of SS7-based theft of banking SMS codes in Germany (2017) and of SIM-swap fraud cases.
- Positive Technologies and Syniverse/Mobileum/Enea/AdaptiveMobile threat reports on SS7, Diameter and GTP.
- EU 5G Toolbox (2020) — risk-mitigation measures for 5G network security.
- ENISA — Threat landscape for 5G networks and related reports.
8. How to use these references
- For a message or field (e.g.
SendRoutingInfoForSM), open the protocol spec (MAP: TS 29.002). - For a procedure (attach, handover, registration), open the architecture/procedure spec (TS 23.401 for 4G, TS 23.502 for 5G).
- For numbers and formats (IMSI, GT, MSISDN) use TS 23.003 and ITU E.164/E.212.
- For security guidance use the GSMA FS documents and the security specs (33.xxx).
- For unknown acronyms use the glossary page of this site.
9. Additional references for the newer modules
| Topic | Reference |
|---|---|
| Satellite / NTN | 3GPP TR 38.811 (NR to support NTN), TR 38.821 (solutions for NR-NTN), TS 38.300 NTN sections; ITU Radio Regulations; ITU-R S. series; ESA/ETSI SES documents |
| Wi-Fi | IEEE 802.11-2020 and amendments (ax, be, ah, bf), Wi-Fi Alliance technology pages, WPA3 specification |
| Bluetooth / short range | Bluetooth SIG core specification (5.x), NFC Forum specifications, FiRa Consortium (UWB), IEEE 802.15.4 |
| LPWAN / IoT | LoRa Alliance LoRaWAN specification, 3GPP TS 36.300 (NB-IoT/LTE-M) and TS 23.682, OMA LwM2M, OASIS MQTT 5, IETF RFC 7252 (CoAP) |
| Fixed access | ITU-T G.984 (GPON), G.9807.1 (XGS-PON), G.987 (XG-PON), G.989 (NG-PON2), G.992/G.993 (ADSL/VDSL), G.9701 (G.fast), CableLabs DOCSIS 3.1/4.0 |
| Optical transport | ITU-T G.652 (single-mode fibre), G.694.1 (DWDM grid), G.709 (OTN) |
| Ethernet / IP / MPLS | IEEE 802.3, 802.1Q, IETF RFC 3031 (MPLS), RFC 4271 (BGP-4), RFC 8200 (IPv6), RFC 6146 / 6877 (NAT64 / 464XLAT), MEF service specifications |
| Radio engineering | 3GPP TR 38.901 (channel models), ITU-R P. series (propagation), Hata/COST-231 models, ICNIRP 2020 guidelines |
| Public safety / PMR | ETSI TETRA (EN 300 392), ETSI DMR (TS 102 361), 3GPP TS 22.179 / 23.379 (MCPTT), TS 23.280 (MCX common) |
| Railways | UIC / ETSI GSM-R specifications (EIRENE), UIC FRMCS documents, ERA ERTMS/ETCS pages |
| V2X | 3GPP TS 23.285 / 23.287, ETSI EN 302 637-2/3 (CAM/DENM), SAE J2735 |
| Emergency calls | Directive (EU) 2018/1972 (EECC) articles on 112, EU eCall Regulation (EU) 2015/758, 3GPP TS 23.167 (IMS emergency) |
| Regulation (EU) | EECC Directive (EU) 2018/1972; GDPR (EU) 2016/679; ePrivacy Directive 2002/58/EC; Open Internet Regulation (EU) 2015/2120; Roaming Regulation (EU) 2022/612; NIS2 Directive (EU) 2022/2555; RED 2014/53/EU; Gigabit Infrastructure Act (EU) 2024/1309 |
| Croatia | HAKOM publications (quarterly market data, spectrum decisions, numbering plan "Plan adresiranja" NN 45/2023, 5G pages); Zakon o elektroničkim komunikacijama (ZEK) in Narodne novine |
| Lawful interception | ETSI TS 102 232 series (handover), TS 133 106/107/108 (3GPP LI) |
| Protocol analysis | Wireshark user guide and protocol pages (wiki.wireshark.org), 3GPP TS 24.301 / 24.501 cause tables, IETF RFC 6733 (Diameter), RFC 3261 (SIP) |
10. Sources checked while verifying this guide
These public pages were consulted to confirm specific facts (titles of GSMA documents, dates of first launches, Croatian 5G auction, EU roaming limits). Spec numbers elsewhere come from standard knowledge and the official portals above.
- GSMA interworking security overview and documents FS.07, FS.11, FS.19, FS.20, FS.21, FS.52 (gsma.com → Security → Interworking Security).
- 3GPP specification database entries, e.g. TR 23.840 Study into routeing of MT-SMs via the HPLMN (3gpp.org/dynareport/23840.htm).
- GSMA announcement of the first interconnected VoLTE service in South Korea; first commercial VoLTE launches in August 2012 (SK Telecom, LG U+, MetroPCS).
- First commercial 5G: South Korea (December 2018) and US fixed-wireless (October 2018); mass-market phone launches in 2019.
- HAKOM: "5G network in Croatia" and the August 2021 spectrum assignment (700 MHz, 3.6 GHz, 26 GHz; 15-year licences; about HRK 359 million); HAKOM quarterly market data for 2024–2025 (operator shares, penetration).
- European Parliament Legislative Observatory summary of Regulation (EU) 2022/612 (roaming to 2032, wholesale caps).
Illustrative values, sender names and numbers in this guide are fictional. Operator code assignments (MCC/MNC) change; verify them in the ITU and GSMA lists before relying on them.