Thank you to reply. I forgot to say, in 4days before it was working, and i could hear one way voice(outgoing call in dialing, and incoming voice when answer call), also i could play wave file, and record conversations. I do not know what happened exactly, but i guess i changed modem .INF file in trying to full-duplex support, and all failed after it, then i reinstalled previous modem. Also i do not know about ACM Codecs, i google it when i be in my work place. Thank you again!