How does AMR Bandwidth efficient mode looks like?

 In the payload, no specific mode is requested (CMR=15), the speech frame is not damaged at the IP origin (Q=1), and the coding mode is AMR 7.4 kbps (FT=4).  The encoded speech bits, d(0) to d(147), are arranged in descending sensitivity order according to [2].  Finally, two padding bits (P) are added to the end as padding to make the payload octet aligned.




references:
https://tools.ietf.org/html/rfc4867