Additional information:
The following applies to stored-file transfer methods:
Magic numbers:
single-channel:
ASCII character string "#!AMR\n"
(or 0x2321414d520a in hexadecimal)
multi-channel:
ASCII character string "#!AMR_MC1.0\n"
(or 0x2321414d525F4D43312E300a in hexadecimal)
File extensions: amr, AMR
Macintosh file type code: "amr " (fourth character is space)
According to https://tools.ietf.org/html/rfc4867, the mime type can have the following file extensions:
amr
,AMR
.