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The Guide to do A-interface voice loop on

BSC32 platform

Pakistan Wireless TAC

Huawei Technologies Co., LTD.

Nov, 2009

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Call muting issue is a very common issue and not easy to handle. Many reasonscan cause call muting, for example: 1. Abis timeslots configuration mismatch

between BSS and transmission; 2. RF interference, receive quality/level; 3. Ater/A

interface E1/CIC cross patching; etc.

If call muting is only observed on single site, then it is easy to do the

troubleshooting: Verify ABIS timeslots, transmission quality, do TRX level call test,

etc

If call muting is observed on multi-sites, normally the issue is on BSC level or

above (MGW/MSC)

For BSC6000, it is easy to troubleshooting BSC level call muting via the function

Remote Speech Channel Loopback& DSP Speech Channel Loopback.

For BSC32, we can also do the A-interface Loopback (Need enter super-mode

first).

The following is the procedures:

1. Close all the M2000 client, launch "Local NE management system", login to

BSCH06SWL with "OMC" account or other accounts with administrator permission.

2. Local NE management system-->Start--> System--> System Configuration

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In the setting window, type "Ctrl+F10", then enter the password "ThisIsTony",

then you can login as super mode

3. Then start--> Task--->Maintenance

4. Do the call test and do "BSC User trace"

From the call trace, you can get the CIC in the message

"ASSIGNMENT_REQUEST",

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click on the message, then go to the bottem of the message, click "PCU multiplex

in use", then in the below window, CIC bytes will be highlighted, for example,

02AF ---> convert to decimal is 687

5. Then you can check data-configuration, double-click on the FTC board, you can

find the CIC configured on which FTC board.

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6. When do the call test, for example, one engineer move to site ,call another

engineer in OMCR/NOC, when call muting is observed, don't hang-up the call, find

the CIC from the "Assignment request message", then from maintenance module,

find the FTC board on which the CIC is configured, right click on the board, and do

the A interface Loop-back.

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Type the CIC that was assigned to the muting call

If loop to BSC side, and the caller(on site) can hear his own voice, then call mute

issue is on A-interface or above(MSC/MGW side),Most possible reason is CIC notmatch on A-interface; otherwise, call mute is caused by BSS.

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