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Topic Title: Voice Monitoring of Ater over chSTM-1
Topic Summary: Looking for a field test unit for the in service monitoring of voice paths
Created On: 30 June 2010 11:09 PM
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 30 June 2010 11:09 PM
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kennethhalley

Posts: 10
Joined: 05 June 2006

Hi
A practical conundrum.

I was wondering if any of my iet colleagues know of any sort of tester for monitoring Ater voice traffic in service where its carried over a chSTM1 bearer.
I do understand the technical complexity of the task at hand, however the requirement still exists. Up until fairly recently voice channels were monitored on the A interface between the trasncoder and the MSC using conventional E1 test units like the GN Nettest Elmi Lite 3000. When a spot of renetworking was done the practice was for technicians to physically check each link by monitoring a random selection of speech channels in each A interface listening for 2 way speech. This was to ensure we did not have crossed paths resulting is setups and one way speech paths. When renetworking was done in the middle of the night, the volume of traffic was often too low to detect the improper clear codes from the MSC until call volumes rise mid morning time. Physically monitoring circuits has proved effective in such tasks over many years. A interface speech is basically G711 PCM format.
We now have a migration of GSM E1 based traffic onto R4 MGW's and the A interface is no longer exposed. Only the A ter interface. However this is presented over a chSTM-1. The same hazard of incorrectly configured circuits still exists and the request from our service management teams is that they require voice path monitoring following renetworking.
We have optical monitor points in place but no means to check voice paths.
I am aware of equipment that would allow us to extract E1's from the chSTM1 and then further chain on to other kit which in turn would be capable of decoding the transcoded speech from the E1. However in general this equipment is really protocol analysis test gear and not something one would wish to purchase in volume for field test. I am looking for some sort of hand held unit akin to the Elmi Lite 3000, or like a Sunrise SDH test set, with this capability. I know this is a tall order but I am being pressed from failry high up the food chain for cost effective solutions. I have spoken to a number of test equipment vendors with no luck so far. I also understand that the push towards All over IP solutions is likely to render such a solution obsolete in the fairly short /medium term but again this does not remove the requirement.

Answers on a postcard Anyone?

thanks

Kenny Halley MIET MBCS CITP

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Kenneth Halley MIET MBCS CITP
Principal Engineer
Core Network Support
UK (Scotland)
 23 July 2010 07:35 PM
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finky

Posts: 11
Joined: 23 January 2009

Kenny,

Try these guys, I expect they can help.
Google them for the website.
Malden Electronics Ltd
2 High Street
Ewell
Surrey
KT17 1SJ
England
Telephone: +44 (0)20 8786 9145
Ask for Ron or Richard

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Chris Fink I.Eng MIET
 28 July 2010 10:08 AM
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kennethhalley

Posts: 10
Joined: 05 June 2006

Thanks for this: will have a look. I have discussed this issue with a number of the big test gear suppliers and the few that have anything have only got some form of two box solution ( or in fact- four box solution- where two boxes are needed in each direction of traffic flow) involving a demux stage from chSTM1 into E1 with the TRAU frames then decode from there. This does not seem terribly useful as an easy to use field test set. In addition what they offer tends to be an ability to make measurements at the test point rather than the ability to physically tap onto the call and listen in to whether its working or not (real time voice monitoring)
As most vendors are pushing towards tools for an all IP world there seem to be few who are interested in providing the solution I need. Having said all that I have heard of one vendor who thinks they may have a single box, field useable solution that might do what I need in a few months time as it was developed for a large European Network provider with the same requirement as me, if this proves successful I will update here.

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Kenneth Halley MIET MBCS CITP
Principal Engineer
Core Network Support
UK (Scotland)
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