Quality of calls to Mobiles (Distortion)

[MightyRed]

One of our customers had a custom built Cisco system running via a PC possibly asterisk, not sure exactly what.

This works 100%.

We installed an IPO 500 at the start of the year on 4.1. The cards installed were Phone2, VCM32 and an old PRI on legacy card carrier. They also have CCC, ContactStore and Voicemail Pro. They were using a Cisco PoE switch, which we have tried changing to a 3com PoE switch for testing.
When making and receiving calls to and from mobiles there is a distorted echo. When you are speaking you can here yourself in the background distorted.

For example
If they phone me and i go one, two, three etc, after i have said one there is a short burst of distorted echo of me saying one. Every time i say something there is a modulated echo straight after.

This is not related to call recording, I have tried disabling this, with no change. It also happens on the analogue devices.

The customer decided to reinstall his Cisco system. No faults occurred for months.

Yesterday we got another chance. I went back to site with a completely new IPO 500 on 4.2(4), new Phone2, new VCM32 and a IP500 PRI. The fault still occurred.

All the IP phones are 5610's, I upgraded all phones to the new firmware.

We've tried altering GSM silence suppression.
We've tried altering the AGC setting on the handsets.

Any ideas??

http://www.nemesisnetworks.co.uk

 

[TLDuk]

If you have access to an ISDN tester I would test both the system and the lines with it first..

 

[MightyRed]

I forgot to take the ISDN tester with me yesterday, but we have tested the lines before and no fault occurred.

I have got the original system in the office. Unfortunately we can't test it with ISDN30 lines as these are connected to our in house system. We have got ISDN2e in the office for remote access, so i have installed a BRI4 and tested dialling out on a 5610 and a 5602 using this.

We have tested calling mobiles several times and no fault has occurred.

The problem we have is, as soon as the customer reinstalls his custom built cisco, and connects the ISDN30 the faults disappear.

http://www.nemesisnetworks.co.uk

 

[TLDuk]

Try enabling GSM Silence suppression in the system telephone tab..

other than that try adjusting the VCM settings also in the system tree..

The reason I mentioned the ISDN tester was to see if you intercept the call can the distortion be heard on the ISDN tester or only on the phone connected to the IP office


If it not broke tweak it..

 

[MightyRed]

I tried the GSM silence suppression yesterday. Didn't make a difference whether it was ticked or unticked.

I don't think altering anything in the VCM settings would change it, as we also got the fault when an analogue phone was connected to the Phone 2.

When originally occurred our first instinct was the lines, but the tests came back clear and the customer put the Cisco back on and it worked ok.

http://www.nemesisnetworks.co.uk