[Asterisk-Users] Asuscom HiSax based ISDN BRI card - one way latency

[Martin 'poorman' Klozik]

Hi all,

I have configured Asterisk server with Asuscom ISDN card and 1 port TDM10B 
card. ISDN card is based on HiSax chipset and it runs with hisax kernel 
module. When call from 'zap/1' phone (or any SIP client) to PSTN is connected 
next behaviour occurs:

- PSTN station hears 'zap/1' with latency (about 1 sec)
- 'zap/1' hears PSTN station without latency

I've spent a lot of time by tracing the cause. A few minutes ago I've find 
something really strange. When kernel module is loaded and asterisk run (e.g. 
asterisk -c) it works fine. Once you connect to running asterisk server by 
'asterisk -r' then one way latency starts! The only way to get a rid of 
latency is to stop asterisk, remove hisax module and start all again.

I've tested Asuscom ISDN card (HiSax: HFC-PCI card manufacturer: 
Asuscom/Askey) and Eicon Diva (HiSax: Eicon.Diehl Diva driver Rev. 1.1.4.2).
Asuscom works as described. With Eicon card there is no latency at all. It 
doesn't matter if remote connection to asterisk was made or not.

Any ideas why remote connection to asterisk server confuses Asuscom ISDN card? 
Why Eicon Diva is not affected? It uses the same chipset and kernel module...

My configuration:
PC: Athlon XP 2200+, 512MB RAM, Debian-stable (Woody), Kernel 2.4.22
Asterisk - updating continuously from CVS - I get the same behaviour over two 
months
modem.conf is as follows (nothing special):
[interfaces]
driver=i4l
type=autodetect
dialtype=tone
mode=immediate
stripmsd=0
group=1
msn=xxxxxx
context=isdn
device => /dev/ttyI0
device => /dev/ttyI1

Thank you, poorman