isdn-problems between uk and germany

[orish]

HI all,

my customer has 1 PCS-1 (ver2.4) in UK and 1 PCS-1 (ver2.4) in Germany. If the UK calls into Germany sometimes there is no picture, sometimes there is picture but picture freezes after 1-2 seconds, sometimes it works fine. In other direction there is no problem.

I checked the settings of both systems and the isdn-settings are well configured.

Does anybody know if quality of lines could be the reason of this behaviour? Sometimes - when they have frozen pic - the see red, green, violet dots in blocky pictures and I know that this could be indicating bit failures of the isdn-line.

So, what should I do to get closer to the reason? At the Moment the will make a long term measurement of the lines over the weekend.

Any suggestions?

Thanky very much
orish

[Glen Sykes]

In many cases it is the carrier that is at fault, and the reasons can be varied.

I have seen this several times on our MCU service. To overcome it we operate diverse networks so we can route our traffic over different providers networks.

It's most commonly seen with calls to and from north america where carriers have a habit of sending calls down compressed circuits unless you tell them that you need data end to end.

We used to have a similar problem in Europe which was overcome by dialling three zeros before the country code instead of the usual two. A bit of useless but nonetheless interesting history!

[orish]

keep updating.

cheers
orish

[orish]

The isdn lines are not compressed - its data service. The BT did some testing an the result is that isdn calls from UK to Germany were routed to Frankfurt or to Duesseldorf (load balancing I think).

If the calls were routed over Frankfurt all things are fine, are they routed over Duesseldorf the behaviour above appears.

So, question is how to check that all calls of my customer are routed over Frankfurt?!

Any hints?

thanks orish

[Bond]

The channels can´t frame sync, if running different routes.
Sony codec have a low tolerance regarding runtime variations between channels.

BT has a very poor direct peering to the German Telecom
(rumors say 1 PRI only) If this is filled, non-direct routes are used.
Did they check all channels (running via Dusseldorf) or the 1st one only ?

One has to avoid splitting the channels of a call, e.g. 1-2 over route 1 (filled up) and then 3-6 over route 2.

MCU operator´s dirty trick: call several times German test numbers and let it up until you get a non-sync call. Then make the call you want and if it is stable, release all others

The best solution: The Germans should call back. I use a German MCU