Where can anyone read the official specifications of the mobile network generations (GSM, UMTS, LTE, 5G)?
All specifications are freely available on the 3GPP website (www.3gpp.org) — every generation, every protocol, every release.
The 3GPP (3rd Generation Partnership Project) is the standardization organization behind GSM, UMTS, LTE, and 5G NR. Unlike many industry standards (ISO, IEEE), 3GPP specifications are published for free — anyone can download the complete technical specifications.
How the releases work:
- Specifications are organized in Releases — e.g., Release 99 is the initial specification of UMTS (3G), Release 8 is the first LTE spec, Release 15 the first 5G spec
- Each release contains hundreds of numbered Technical Specifications (TS), e.g. TS 24.008 for the mobility/session management protocols
Why this matters for security work: When researching a mobile vulnerability or implementing a protocol tool, the primary source is always the 3GPP spec — not blog posts. Open access is also why open-source mobile stacks (like Osmocom, the project of Harald Welte) could be built: the "secret" protocols of the phone in your pocket are actually publicly documented in full detail.
Resource: https://www.3gpp.org/specifications — or the spec-number search at https://portal.3gpp.org
Go deeper:
3GPP — The system of parallel releases — how Release 99, Release 8, Release 15… map to UMTS/LTE/5G, the primary-source authority for any spec number.
Osmocom (Wikipedia) — the open-source GSM stack (Harald Welte's project) that exists precisely because these specs are public.