Call interruptions

Emin Gabrielyan

Switzernet

2008-11-18

In past several months we are receiving complains from customers about phone calls being interrupted after several minutes of conversation. Since the beginning of November our support already counted 20 different complains on this subject.

This problem is very difficult (rather impossible) to reproduce in our premises. We are still not able to locate the source of the problem. Our engineers have the intention to investigate the problem more closely. Since we cannot catch the problem ourselves on our test phones and analyze the call progress on the protocol level, we can presently work only on statistical researches in attempts to understand the problem better.

A simulation demonstrates how statistical researches may give more information on the problem. The chart below shows a distribution of 14’000 calls according to their durations on a scale consisting of 10-second intervals. The simulator is programmed to interrupt calls on the 10th minute of conversation with a probability of 5%. The distribution curve reflects the random interruptions occurring with calls at 600^th second of conversation.

The parameters of simulation can be changed in the excel file [zip] and the chart can be reconstructed.

The study of real traffic may lead us to the problem.

References

Call interruptions (this page):

http://switzernet.com/public/081118-call-interruptions/

http://unappel.ch/public/081118-call-interruptions/

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