AMR-WB / G.722.2
AMR-WB is mandatory for VoLTE — every LTE voice call uses it. Understanding rate adaptation and the AMR payload format (RFC 4867) is essential for mobile VoIP and operator codec policy.
What It Defines
Adaptive Multi-Rate Wideband (AMR-WB) is the mandatory codec for HD voice over LTE (VoLTE) and UMTS. Operates at 9 bitrates from 6.6 to 23.85 kbps with adaptive rate switching. Also standardized as G.722.2 by ITU-T. AMR-NB (narrowband) covers 4.75–12.2 kbps for GSM fallback.
Canonical (Normative)
Related References
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.
Related Specs
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