What about speex codec bandwidth? How can i optimize it?

Speex uses quality 6 on client. It’s codec bw: 20kbps
https://github.com/flashphoner/flashphoner_client/blob/rtmfp/client/api/src/com/flashphoner/api/SoundControl.as

See the table: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/media/Microphone.html

Server uses speex_in_policy=8,false,8,4,true
if speex encoding is needed. So, quaity is 8 and bw is about 30 kbps.
See more here about the setting: http://docs.flashphoner.com/display/WCS2/Tuning#Tuning-DownstreamisastreamfromFlashServertoFlashclient

Note, 20kbps and 30kbps are pure codec bandwidth.
There is an additional overhead added by RTMFP and RTP headers.