56K instead of 64K?

[Airwave1]

Hi,

Been having a few problems with one of our units.
Its a Tandberg 880 and uses ISDN6, its usually very reliable but recently we have had quite a few conference where is has only connected at 336K instead of 384K. This would suggest that each line is only connecting through at 56K instead of 64K.
I have checked and the unit is not set to resrict to 56K so its doing it automatically.

Has anyone else experinced these types of problems and if so what conclusion did you draw?

Thanks!

[tom9933]

We have a problem similar to this when we call one specific site. It seems that there is an issue between two of the local phone offices where the path is only 56k capable rather than 64k capable. We tried to explain the problem to the local phone company and they promptly passed the buck to the other carrier so we have not been able resolve the issue. We didn’t put a lot of much effort into this because the site is a local reseller and I was only making the calls to try and test our ISDN connectivity. If it’s a similar problem then you may have a fun little battle on your hands.
Good luck,

[Hariharan.I.D]

Hi,
I have faced similar problem with a Swiftsite II of Picturetel
around a couple of years back.
It got rectified by updrading the unit to the newer version.
I dont remember what were the version numbers.
refards
Hari
















Been having a few problems with one of our units.
Its a Tandberg 880 and uses ISDN6, its usually very reliable but recently we have had quite a few conference where is has only connected at 336K instead of 384K. This would suggest that each line is only connecting through at 56K instead of 64K.
I have checked and the unit is not set to resrict to 56K so its doing it automatically.

Has anyone else experinced these types of problems and if so what conclusion did you draw?

Thanks![/QUOTE]

[Airwave1]

What is strange about this is that its intermitent. If it was always happening then I could do more about it, like speak to the ISDN providers at both ends.

Just wandered if anyone had come across this happening before.

Thanks

[WIZBANG]

If there are multiple trunks between the central offices, some may be only 56K capable. I have also had problems when phone companies use older 56K circuits as overflow when 64K channels are all in use.

Is there a pattern of 336K calls happening during certain times of the day? If circuits are congested the calls may be routed differently.

If multiple paths are involved, the best way to fix the problem is to have the ISDN provider enable 1 circuit at a time while test calls are made to find the 56K only circuit. Usually needs to be done at night when there is little traffic. Starting a trouble ticket with the provider suggesting they check all circuits that the calls can possibly be made down and compare the programming to be sure all are 64K capable is also an option but likely to get shot down by the provider, it's easier for them to blame another provider or the endpoint equipment.

[vtjoe]

Hello Airwave1,

Are you recieving or placing calls when you get 336k? The Tandberg will connect at 56k for three reasons:
1) you told it to (which you did not)
2) It sees 56K on the lines directly connected to it and is placing or recieving the call.
3) It is recieving a 56k restricted call.

What these leave out is the scenario where you get 56k because it is being dropped from 64 to 56k due to congestion between COs (e.g. long distance carrier). When this happens, you will get tiling or screaching audio, or no connection at all. The fix then is to force it to 56k call.

Here is the most important question, other than the banner "Connecting 336kbps" can you tell the difference between the 384 and 336 call? If not, I wouldn't worry about it.

[Sean Lessman]

Hello Airwave1,

Are you recieving or placing calls when you get 336k? The Tandberg will connect at 56k for three reasons:
1) you told it to (which you did not)
2) It sees 56K on the lines directly connected to it and is placing or recieving the call.
3) It is recieving a 56k restricted call.

What these leave out is the scenario where you get 56k because it is being dropped from 64 to 56k due to congestion between COs (e.g. long distance carrier). When this happens, you will get tiling or screaching audio, or no connection at all. The fix then is to force it to 56k call.

Here is the most important question, other than the banner "Connecting 336kbps" can you tell the difference between the 384 and 336 call? If not, I wouldn't worry about it.

Typically one of two things will happen if you dial clear channel (64k) and get a restricted channel call (56k). The network will reject the call altogether, or the call will connect with one endpoint at 64k and the other at 56k. Then the units will communicate and realize the call is at 56k and the 64k site will drop to 56k. Both behaviors are possible in the US network depending on whose network the call passes through. 56k networks are typically AMI encoded which is a technique used to take old 1970's networks and provide digital service. 'True' digital service will give you 64k all the way through.

Sean