FXS coefficients file types:

1) MP1xx13-1-fxs16khz.dat - relevant for any MP1XX, supporting generation of 16 KHz metering tone.
2) MP1xx13-1-fxs12khz.dat - relevant for any MP1XX, supporting generation of 12 KHz metering tone.

* If metering type (16Khz or 12 KHz) is not important, it is recommended to use coefficients file number 2.

