Chan_mobile connects, no audio: sco_read/write not ready and error 107

My goal is to make a phone call from phone gsm to a laptop passing by asterisk (sip) and chan_mobile bluetooth on raspberry pi 2,the call passes from phone 1 to phone 2 via gsm then phone 2 transfers the call over bluetooth chan_mobile to raspbx then raspbx transfers the call to the sip client (laptop) worked fine and zoiper rings, the thing is i can play music through and i can hear it from raspberry jack, but when i call i can’t hear the caller and the caller can’t hear me, after doing core set debug on asterisk console i got 2 errors :
1- chan_mobile.c:819 mbl_write: *** mbl_write
chan_mobile.c:1149 sco_write: sco_write() not ready
and this error appears when the phone is ringing
2-chan_mobile.c:1175 sco_read: sco_read() error 107 and error 104
and this error appears when i pick up the phone

i searched the internet and i found that so many people having the same problem but with no solution found exemple : http://forums.asterisk.org/viewtopic.php?f=1&t=23594&start=0

im using Asterisk latest version freepbx on raspberry pi 2
a bluetooth usb dongle
zoiper as sip client on windows 10

all help will be appreciated. Thank you !