The AMR (Adaptive Multi-Rate) codec encodes narrowband (200-3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbps with toll quality speech starting at 7.4 kbps. AMR is the required standard codec for 2.5G/3G wireless networks based on GSM (WDMA, EDGE, GPRS).
It was initially developed for GSM and has been standardized in 1999 by European Telecommunications Standards Institute ETSI
In 2006 it was included in the CableLabs PacketCable 2.0 specification.

Resources

• Wikipedia AMR
• VoiceAge AMR page

See Also

• Codecs
• Asterisk Codecs