Fax transmission through Patton and Asterisk

Hi,

I’ve a fax attached via DAHDI to Asterisk connected to a Patton. I’ve problem with sending and receiving fax, this is my configuration:

profile voip default
codec 1 g711alaw64k rx-length 20 tx-length 20
codec 2 g711ulaw64k rx-length 20 tx-length 20
rtp traffic-class default
fax transmission 1 bypass g711alaw64k rx-length 10 tx-length 10
fax redundancy low-speed 2 high-speed 1
fax dejitter-max-delay 300
fax max-bit-rate 9600
fax detection fax-frames
modem transmission 1 bypass g711alaw64k rx-length 10 tx-length 10
modem bypass-method v150-vbd

Any suggestions?
Regards