I worked for a company called TopTel, managed the VC networks for ICL, DOH and few others, dealt with many Telco's and bridge companies who's names escape me at the time. international VC and dialing the extra 0 for ISDN lines to make sure they didn't route over satellite and then the fun of switched ISDN (North American ISDN standard with it's bit stealing 56k lines over the dedicated D channel 64k lines). Fun times.
One aspect of VC was you could tell if a network link (leased lines) was not upto scratch as you would see bit error, unlike network data, which would happily gloss over such odd bit errors. Other fun and games was ISDN circuits being stolen due to engineers repatching lines of little used circuits and then when the ISDN would lock up and that would often be that the bit error count hit a limit. You would call up, get the telco to test the line/circuit and low and behold it would be working again, this was due to the test resetting the error count. Had a neat way of testing lines using my 2G mobile on the Orange network, in that if I called an ISDN line the way it terminated the call would indicate if it was up or was errored, or busy.
But my funniest story would be spending 30 minutes trying to resolve an issue with a PicturTel setup with some French chap and why the audio from his end was not working, turned out he was sat upon the microphone.
My company and I could have used your knowledge! Got sent to Europe to debug some problems where we had an ISDN card from a third party installed in our systems and got to visit UK, Germany, Belgium, and France to look at different issues.
One aspect of VC was you could tell if a network link (leased lines) was not upto scratch as you would see bit error, unlike network data, which would happily gloss over such odd bit errors. Other fun and games was ISDN circuits being stolen due to engineers repatching lines of little used circuits and then when the ISDN would lock up and that would often be that the bit error count hit a limit. You would call up, get the telco to test the line/circuit and low and behold it would be working again, this was due to the test resetting the error count. Had a neat way of testing lines using my 2G mobile on the Orange network, in that if I called an ISDN line the way it terminated the call would indicate if it was up or was errored, or busy.
But my funniest story would be spending 30 minutes trying to resolve an issue with a PicturTel setup with some French chap and why the audio from his end was not working, turned out he was sat upon the microphone.