asterisk users - Jan 2005 - Problems using chan_capi over Fritz!Bluetooth

Dear all,

all you chan_capi users out there, has anybody a AVM Fritz!AP-ISDN
working with Asterisk?
The sound on the outbound side is very stuttering (not possible to
understand). Muting the remote end did not have any effect while muting
the local end stopped giving me below errors:

chan_capi.c:955 capi_write: error sending DATA_B3_REQ (error=0x1103,
datalen=160) B3in=6
chan_capi.c:955 capi_write: error sending DATA_B3_REQ (error=0x1103,
datalen=160) B3in=4
chan_capi.c:955 capi_write: error sending DATA_B3_REQ (error=0x1103,
datalen=160) B3in=3
chan_capi.c:955 capi_write: error sending DATA_B3_REQ (error=0x1103,
datalen=160) B3in=1

I once read something about filled-up buffers and/or lost interrupts.
Anything I can do about this?
(A Fritz!Card-PCI is working perfectly fine)

Here is my config:
asterisk-1.0.3
chan_capi-0.3.5
capi4linus-3.11
Bluez-2.13 (using cmtp)
Fritz!AP-ISDN and a USB-BT-Plug from Shuttle (no interrupt sharing on
the USB)

Thanks for any hints!

Regards,
Alex