2 Problems. Get PSTN Line (from DAHDI). Noise in initiation receive call

Hi for all.
I have 2 problems in my setup.

1. When in analog device (DAHDI) i press 0 and after some seconds i got tone from PSTN line.
   If i press 0#, is instantly .
   How i can insert 0# when user press only 0.

2. When i receive a call, a disturbing noise occur. Is about 1-2 seconds only and the call is back to normal. What can be ?. When i made a call, it's normal (no noise or echo).

Thanks.