echo cancellation / suppression in chan_capi & isdn4bsd by HPS

[Oliver von Bueren]

Hi Michael

Michael Iedema wrote:
> - echosquelch - activates some "light" echo cancellation in the
> chan_capi code itself
>   
I have set this to yes in capi.conf (and only this, all others don't 
work for me at all)

Next thing I did to improve the echo situation on calls from IP phones 
to ISDN is to change a default value in i4b_global.h from 9 to 10:
#define I4B_ECHO_CANCEL_P_COMPLEX  (10)
Without that, it was pretty bad and my wife complained!

You'll find this file in /usr/src/sys/i4b/include
After the change you have to compile the kernel, I usually do this with:
# cd /usr/src
# make buildkernel installkernel KERNCONF=YOURKERNEL -DNOCLEAN -DNO_CLEAN"
 
BTW: I've got an AVM Fritz Card on a Point2Point ISDN BRI from our 
national telco provider.
# isdnconfig
controller 0 = {
  Layer 1:
    description : AVM Fritz!Card PCI
    type        : passive ISDN (Basic Rate, 2xB)
    channels    : 0x3
    serial      : 0xabcd
    power_save  : on
    dialtone    : enabled
    attached    : yes
    PH-state    : Activate indication (priority=8/9)
  Layer 2:
    driver_type : DRVR_DSS1_P2P_TE
}

The only negative thing I have is that I can't reboot without loosing a 
channel on the card. After a reboot one channel stays dead. It looks 
like the initialization of the card isn't reaching the same state after 
a cold vs. warm reboot. Anyway, I'll have to get something more decent I 
think.

       Oliver