Issues with echos LCR <-> Asterisk

Hello.

I have an issue with the Linux Call Router in combination with asterisk 
(chan_lcr) and I hope I am right here.

First, my set-up is a dedicated host with Ubuntu 12.10 with the latest 
and greatest git versions of mISDN, mISDNuser and the lcr software 
installed. The lcr manages a quadbri using mISDN with a ptmp NT port 
connected to an Gigaset Basestation and a ptmp TE port connected to the 
Telekom. (Some more data is attached at the bottom of the mail.)

The interfaces for mISDN are configured straight forward 
(/etc/lcr/interface.conf):
[isdnext0]
extern
portnum 0

[isdnint0]
extension
portnum 1
nt

Additional to the ISDN card I connected an Asterisk 
(1.8.13.1~dfsg-1ubuntu2) using the chan_lcr plugin.

[astint]
remote asterisk
context incoming-lcr
extension
earlyb no
tones yes
screen-out national % 0%
screen-out international % 00%

Everything works fine if I stay in the ISDN world. Calls go out and in 
without any bad happen. But if I inter-connect between asterisk and lcr 
(e.g. SIP client <-> ISDN Phone), I hear an echo of my own voice on the 
SIP side only, even if the remote side is muted. Since I tested this 
with SIP clients only, I checked SIP <-> SIP too and got no echo there. 
Further, I tried different SIP clients (Gigaset S450 IP, Android Phones 
and a SoftPhone for Linux), all with the same result.

During my search for a solution, I tried to switch on the echo 
cancellation by adding "filter pipeline oslec" to the "astint" 
interface, but this does not changed anything.

Are there any known solution for echo issues on chan_lcr?
Is anybody out there with a similar set-up without such an issue and can 
send me a working configuration?
How is echo cancellation configured in the recent lcr version? There are 
many changes in the code and the available documentation does not seems 
to match anymore.

Kind regards,
Johannes

PS: Ich nehme auch gerne Antworten auf Deutsch entgegen. :-)


# GIT versions of the source
mISDN git c7bbed7
mISDNuser git 1dc4c24
lcr git 0f05685

# Description of the PCI QuadBRI card
$ lspci -vvv
02:00.0 ISDN controller: Cologne Chip Designs GmbH ISDN network 
Controller [HFC-4S] (rev 01)
     Subsystem: Cologne Chip Designs GmbH HFC-4S [IOB4ST]
     Control: I/O- Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR- FastB2B- DisINTx-
     Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- 
<TAbort- <MAbort- >SERR- <PERR- INTx-
     Interrupt: pin A routed to IRQ 20
     Region 0: I/O ports at 1000 [disabled] [size=8]
     Region 1: Memory at 80000000 (32-bit, non-prefetchable) [size=4K]
     Capabilities: <access denied>
     Kernel driver in use: hfc_multi
     Kernel modules: hfcmulti, hfc4s8s_l1

# Loaded modules
$ lsmod
Module                  Size  Used by
mISDN_dsp_oslec        13089  0
hfcmulti               79813  12
mISDN_dsp             208409  1 mISDN_dsp_oslec
coretemp               13400  0
ppdev                  17073  0
snd_hda_codec_realtek    77876  1
microcode              22803  0
mISDN_core             97578  11 hfcmulti,mISDN_dsp
psmouse                95552  0
hisax                 460979  0
crc_ccitt              12667  1 hisax
serio_raw              13215  0
isdn                  147435  1 hisax
lpc_ich                17061  0
parport_pc             32688  1
snd_hda_intel          33491  0
snd_hda_codec         134212  2 snd_hda_codec_realtek,snd_hda_intel
snd_hwdep              13602  1 snd_hda_codec
snd_pcm                96580  2 snd_hda_intel,snd_hda_codec
snd_timer              29425  1 snd_pcm
snd                    78734  6 
snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_timer
soundcore              15047  1 snd
ext2                   72880  1
mac_hid                13205  0
snd_page_alloc         18484  2 snd_hda_intel,snd_pcm
gma500_gfx            169091  1
drm_kms_helper         46784  1 gma500_gfx
drm                   275528  2 gma500_gfx,drm_kms_helper
i2c_algo_bit           13413  1 gma500_gfx
video                  19335  1 gma500_gfx
lp                     17759  0
parport                46345  3 ppdev,parport_pc,lp
e1000e                199114  0