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Siemens EWSD ability to work

  • This topic has 2 replies, 1 voice, and was last updated 20 years ago by emin.
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  • #26852

    I am working with an operator whose entire network is based on 4 Siemens EWSD exchanges. These exchanges are located in 4 larg cities. Each of the 4 EWSD exchanges is handling approximately 30 to 40 thousand subscribers and 200 million minutes of traffic each month.

    I am connected to this network with 4 ISDN E1, which handles 120 simultaneous calls. In the peak times I have directed a little bit less than a million minutes of traffic to this network a month. Our financial arrangement in the past has been favorable one for me. However, the network operator wishes to reexamine this arrangement. Lately he has established a maximum limit on the number of calls placed through my lines. He has also instituted other measures, which have resulted in the lowering of the quality of the services provided.

    He justifies the above actions by arguing that the traffic directed by me to his network through 4 ISDN E1 was so intensive that he was forced to institute quality and volume limits on my traffic. He says that my traffic volume “imbalances the operation of the entire system ” and “has a very adverse effect on the rest of his subscribers”. I am convinced that these statements are not factually correct and would like to obtain an expert opinion of someone with telecommunication’s industry experience.

    So question is: is it possible???

    David Wray


    Although a million minutes per month over 4 e1’s sounds low it could bring down a switch if it was concentrated to just a few hours each day. It could also bring down the switch if you had a very high call attempt (not connected just attempted.) I hope that helps?

    David Wray



    thanks for the reply. I’m aware of the situation and, concerning the traffic pattern I would say that the distribution over the traffic was quite normal. The traffic generated on those 4 E1s (120 channels in total) never occupied more than 105 channels simultaneously. Ususal occupation of lines were about 50 calls simultaneously at day time and about 5 simultaneous calls at night.

    related to the rate of unsuccessful call attempts: when everything was normal we had an ASR of about 65% to 90%. Once the operator “discovered” that we “overload” its EWSD, he activated a Call Rate Reduction system: (we think the leaky bucket system of EWSD). Our ASR dropped to 10% – 25% (we got a high rate of unsiccessful tries). But with the “leaky bucket” activated the operator is now satisfied and says that now the system is not overloaded. We would like to understand could be it really related with some technical issue?

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