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ISDN loopback numbers

ISDN loopback numbers

ISDN loopback numbers

I'm having some videoconference problems due to bad ISDN quality from Argentina to Italy. Both sites can connect ok to other sites.
I would like to run a BERT test from Argentina to Italy. To this I need a special device in Italy (which I don't have) or a loopback number from a service provider.
For example in Argentina you can call to +54(11)4591-9090 and you will see your own video. And if run a BERT test to that number you only need the test device in one site. To run the BERT test I'm using a Polycom iPower 680.
Do you know of any loopback numbers around the world? (now I need the Italy one but in the future I might need another).
With the information from the test it is easier to open a ticket at our provider.

Thanks and regards,

RE: ISDN loopback numbers

If you cannot locate a suitable loopback number you may be able to put the far end codec into a loopback mode. Most equipment has such a mode so it would be worth checking with the manufacturer.

The closest Loopback number I have to Italy is Germany. Quite possibly this will show the same problem as the trunking form Argentina to Europe probably share the same route - at least to a point.

Germany loopback = country code 49 69 390 409 77

Another trick is to try using 56 kbps versus 64 kbps for each bearer call. Sometimes the different rates have differnet routing tables.

Another thing to check is if it matters if you dial Argentina -> Italy versus dialing Italy -> Argentina.

For more on untangling *network* problems see the white paper titled "Troubleshooting The Public Switched Telephone Network, or, How do you tell the Telco the problem is in their network?"  here:


RE: ISDN loopback numbers

Thanks for the info.
I've check with Polycom but they say it can't be done with the VSX 7000.


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