HiloNC V2 Analog Audio questions


We are using a HiloNC V2 modules for GSM options to our products.
I’d like to have a few more details about analog audio path.

First, a small status of our product:

  • We are using the V4.01 firmware for most of the modules (a few of them might have 2.00 firmware but they are on old products).
  • We can’t change the firmware on product which are already sold (too costly as it require full product disassembly + soldering tool to update the firmware)

Here are my questions :

1/ What is the default gain of the microphone path (‘Input Micro amplifier gain (dB)’ as refered in the technical specification) on pre-V6.00 firmware (I know that starting from V6.00, the +KMAP command works)
2/ If the 16mVrms nominal input level is for the 34dB, what is the nominal input level in RMS for the default microphone gain (the one given as answer to question 1, if different from +34dB). Does it derivate linearly from the points [1.4V / -6db ; 16mV / +34dB] ?
3/ Does the echo-canceller cares about the audio profile set using +VIP command ? If so, is it updated when the +VIP command is sent during a communication (lets say I want to switch from handset to headset during a call, does the echo-canceller will be notified of this change when the +VIP command will be received) ?
4/ What is the best output level setting for the echo-canceller (using the +CLVL command, we currently set the volume to 8, but maybe the echo-canceller is designed to be more effective when using the default CLVL=5 setting) ?

Thanks for your support,

Regards, Jerome