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New Member

Tandberg 800 isdn problems

Hi all,

I’ve a customer with an old videoconference device Tandberg 800 with 3 BRI access that have the following problem:

When i make a video call to another end-point by ISDN , the video call establish but then is always intermittent , one moment I’ve video and audio for 5 seg , after that the video disappear and after 30 seg returns again  , when I’ve no audio it appears that I’ve isdn problems because appears on the screen the message “re-establishing call … please wait” . I tried to isolate the problem , by disconnect one by one isdn access but without any good result. Sometimes I’ve audio but no video but the other side I’ve audio and video.

Can someone help me on this ? Did anybody have a similar problem with any codec with isdn that have this behavior ? “re-establishing call … please wait”

Best regards.

New Member

I would try the following

I would try the following:

When making outbound ISDN calls, check the box for "56K restricted".... or something to that effect

This will attempt to connect at 56K per B channel or 336K

If any segment along the way is not 64K capable it will cause problems that you describe

If it works OK at 336K, then you know what the problems is, getting it fixed may not be easy

If 336K works, you need to determine if its your Local LEC or your Long Distance carrier

The other thing you can try is to place a lower speed call.... e.g 128K or 256K

I have found many cases where the lines were reversed (Line 2 is were Line 3 should be and vis versa) or the SPIDs were entered wrong

New Member

Hi,I tried that you suggest


I tried that you suggest but nothing worked for me.

I tried isolate 1 channel and make video calls from isdn 1 and 2 , 1 and 3  and 2 and 3 , but the behavior was the same.

The isdn numbers  (order numbers) appears to be correct , I connect one by one and make audio calls to and from the isdn number that is in the configuration and works.

I try to make a call with 56k restrict but the result was the same.

Somebody has more suggestions to this problem?

From how many isdn band can I have video calls? 256k?192k? 

Can I do any traces in this codec? Or view all the configuration by cli?

Best Regards

New Member

hmmmmmmStrange that you can


Strange that you can establish the call, but not maintain the connection.

If the call can be established and you can send and receive video / audio...  then lots of things are correct...   wiring, protocol, spids, etc, etc    You are 90% of the way there

I would say that high error rate or timing issues are the most common causes for dropped calls

I read you original post... so the call does not drop, you just lose audio/video sync? is that correct

Are your BRIs direct from your LEC/phone company or are they from a PBX or Adtran MUX?

Do you have the same problem for calls to other ISDN units or just the one system you are testing with?  

I have attached a PDF of an old Tandberg document that describes various diagnostics including ISDN trace.....   I believe these are Tandberg Classic erra docs... not the newer MXP series.   When I did a ISDN trace, it spit it out in hex and I had to use the TISDN.exe file to make it readable ASCII text  (I changed the file ext to .txt so it can be attached.... need to rename to .exe

I would keep it as basic as possible... e.g. 128k non-bonded call, get that to work then build to up to a 384K bonded call....  just my .02 

Good luck





New Member

Yes , the call never fall ,

Yes , the call never fall , just lose audio and video. I try more endpoint with the same beahviour. I sent  in attach one trace off the call , i will read waht you sent me and try to "understant" this hexadecimal trace with  isdntrace on and syslog on.

I can see " H221I-0 connect initial. Start FAW1search " is when i have video and after more or less 5 seg i see in trace "H221I-0 disconnect init " and loose video again and have the message "re-estabilishing call..." on the screen of my LCD.



New Member

Thank you very much for the

Thank you very much for the tool tisdn , now i can understand better my trace , i see the SETUP , SETUP ACKNOWLEDGE , ALERTING , CONNECT and CONNECT ACKNOWLEDGE but for all channels that i have , i think that will be just one setup , not 6 (one for each channel - i have 3 lines 64k x 2 = 384k ). It appears that my bearer cap is correct (data) : Bearer cap: 88 90 and ITU-T, Unrestricted digital information, 64k circuit

In my setups i sent different calling numbers because my 3 access have different numbers.

But even like this , i cant understand the problem , i cant see any messages during the time i have "re-estabilishing call" , during this time just have this type of messages:

00:48.07 3 NT: sapi=0  cr=0 tei=70  RR    nr=12 pf=0
00:57.23 2 NT: sapi=0  cr=1 tei=74  RR    nr=4 pf=1
00:57.24 2 TE: sapi=0  cr=1 tei=74  RR    nr=6 pf=1
00:57.27 1 NT: sapi=0  cr=1 tei=72  RR    nr=12 pf=1
00:57.27 1 TE: sapi=0  cr=1 tei=72  RR    nr=14 pf=1
00:57.32 3 NT: sapi=0  cr=1 tei=70  RR    nr=12 pf=1
00:57.32 3 TE: sapi=0  cr=1 tei=70  RR    nr=14 pf=1


I ask service provider to verify the 3 access and i will wait for an answer from than.

One more thing , does anybody have also the tool "TTH.exe" to analyse the H221 dump ?



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