3GPP Specification Series
3GPP
VoLTE, 5G NR, SMS PDU format, and SIM/USIM specs all come from 3GPP TS/TR documents indexed by series and release.
What It Is
Global mobile standards collaboration. 5-digit spec numbers: first two digits = series (21 requirements, 23 stage 2, 36 LTE, 38 5G NR, 33 security…). Organized by Release.
Taxonomy
Two-digit series × Release (Rel-15…Rel-19) · TS (normative) vs TR (report)
Top-Level Categories
Master Catalog
Sub-Indexes & Guides
The global collaboration of telecommunications standards bodies that produces the mobile network specifications: GSM/EDGE, UMTS/HSPA, LTE/4G, 5G NR, and IMS. Technical specifications (TS) and reports (TR) are freely available at 3gpp.org. Releases (Rel-8, Rel-15, Rel-17…) provide versioned capability sets.
View all bodies →Curated specs from 3GPP
AMR-NB is the fallback voice codec for pre-VoLTE mobile networks and many carrier voicemail systems. The `#!AMR` file header and RFC 4867 RTP framing are distinct from AMR-WB.
EVS is the next-generation carrier voice codec after AMR-WB. Required for 5G voice debugging, operator IMS integrations, and understanding VoNR codec policies.
3GP is the standard container for mobile-recorded video/voice messages, MMS media, and legacy carrier content. Shares ISO BMFF box structure with MP4 but restricted codec set.
GSM underpins SMS delivery, international roaming, and network fallback. Understanding A-interface, MSC, and MSISDN is essential for any telecom or SMS gateway integration.
UMTS/HSPA was the bridge from 2G voice to mobile internet. IMS architecture from UMTS carries forward into LTE VoLTE. Understanding HSPA variants helps debug mobile data fallback scenarios.
LTE is the dominant global mobile network. VoLTE, QoS bearers, and EPC architecture are directly relevant when building mobile-connected applications, IoT modules, or carrier infrastructure.
5G is the foundation for edge compute, private networks, URLLC industrial automation, and mmWave backhaul. Understanding network slicing, SA vs NSA deployment modes, and QoS flows is critical for 5G-connected application design.
LTE-M is the go-to for IoT devices needing voice, mobility, and moderate data rates on cellular. PSM and eDRX power modes directly affect battery life design in firmware and device management.
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