[Asterisk-Users] DTMF noise

[Joseph]

When I try to press any digits there it the noise is as if somebody was
trying to talk to the mic. very close.  Every time I press a digit the
noise follows like an echo.  So the digit I'm entering aren't recognized
by automated systems.

How to control it?  I'm using SPA3000 with a standard phone.
I've tried adjust SPA to PSTN Gain from +6 to -3, no difference.

-- 
#Joseph