Silent calls

[justdream]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G

[RF engineer]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G

Check if you donot have problem in transcoder setting for Speech code type .
BR
RF

[justdream]

Check if you donot have problem in transcoder setting for Speech code type .
BR
RF

how? please explain :hug:

[TEMS]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G

Please check on up-link voice and check on the transmission also like (MW Optic...............)

[cdmauser]

Do you mean GSM? What vendor made the equipment?
It could have many causes, Transcoder or the MSC or the BSC voice coding boards.
I think first a BSC engineer should look at the traces on the BSC and to check if there is anything in the fault files. It should be also checked on the MSC if there are errors reported.

[Cesarus_m]

Is the problem affecting a specific Radio Site?

[justdream]

not specific (the problem affects several sites)
Vendor: huawei

[TEMS]

not specific (the problem affects several sites)
Vendor: huawei

the problem had only new site right ?

[kaizzer545]

in my personal experience.. first I will check the office that are involucrated to the destination call, I agree with TEMS checking Tx, in some cases the trouble begins with crossed cables in DSX or something that avoid the speech, if there is no a Tx problem maybe you could check Transcoders or something at upper level than BTS

[RF engineer]

how? please explain :hug:

you can ask BSS and NSS engineer to check this setting
BR
RF

[mojiiiiii]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G

hello,

i can see 3 main possibilities :
- radio interferences : check if other cells around are using same frequencies
- handover : during a handover the voice is cut, as long as the MS is trying to connect to the target cell. It takes usually less than 100ms, but in case of interferences, it can take longer time !
- i would also check the transcoder alarms

have you been able to reproduce the problem with a drive test tool ? if yes, then you can check the rxqual, FER, and what's going on during the handover.

Ater congestion cannot be the cause (a circuit is either allocated or not, but it doesn't de-allocated during a call : it's a static allocation at call setup)

[mojiiiiii]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G
i would appreciate a little more details.
what do you see during drivetest, will there is "blank" in the voice ??

you don't see anything different ?

then it means the TCH are correctly received, but they contain no voice.

Either the TRX receives voice from TC but due to malfunction, there is no data encoded/modulated in the radio timeslot.

Or the speeh frame received by the TRX is already empty. In this case, the TC is faulty. If it happens randomly on many cells, and randomly during the call, then it's probably a temporary failure of a board.

Could it be connected to DTX (DL or UL) or specific speech codecs (AMR NB, AMR WB ?), or tandem free operation (TFO). All these features require some process within the TC.

try disabling these features for a while, just to be sure

[don_hardiawan]

Dear Sir,...

As I remeber for this case (Huawei vendor)... if this happened only in several sites not all sites (we assume BCCH, BSIC, LAC, CI already corect and site already known in MSC). So please check bellow :

1. Call Control --> Speech Version is same with your BTS version. or modifed in low speech version so can handle many call request.

2. Check the alarm history, if there's any alarm High BER in ATER (usually it located in GIUB or GIUT). if HIGH BER alarm appear it can made impact every call follow this link will have problem (sometimes drop or connect bu silent)

3. Please check in site that having sillent call with Flex Abis Mode. If it setting to Flex Abis make sure Transmission in that site no problem. And for good quali voice ussualy multiplexing mode set to 2:1 if higher than this value will be impact to voice quality.

4. TRX hadware, make sure there no bad TRX problem (you can check with Counter or Genex Nastar).

i hope it can help you......

[plannerguy]

Hi

i had same experince in an area and same was rectified after the TRAU check and . mainly happens due to CIC in MSC , also the TRAU verison if TFO is enabled


Regards
Plannerguy

[zhanglw268]

Has the problem been resolved?

Another consideration is that the E1s/transmission is/are looped.

Regards

David

[miister76]

HI
this problem apear when there cross connection ( transmission side )
do a trace for the mobile and check the E1 connection
BR//

[ahrouch]

We Have the same problem in our network, and almost the case, we found that the problem was in E1 ( Loop, cable, transmission equipement....). So check if the transmission link is OK.

We Have another problem in our network, the FER is High in some sites, znd i want to know, if BAD FER can impact the service, and also which service; PS or CS or Both. Also from which rate of FER wa can judge that FER is BAD

BR

We use HW equipement

[scorpiobgd]

You must check cic allocation on tdm links bro... if it is not paired from both side...

[ahrouch]

How we can chek this?

[scorpiobgd]

I dont know how to check this on huawei ... on eric bsc you can check with command RACIP:

[justdream]

Dears,

Do you hve document about CIC test?
It's not good to ask MSC guys doing CIC test while I'm not aware about it

Kindly share document if you have, thanks a lot

[scorpiobgd]

Before any testing you must do printout of cic-s on bsc and msc guys must do same on msc ...
here is sample printout on msc...

CIRCUIT(S)

TERMID ORD CTRL HGR STATE CIC UNIT

1270-1 1 Y 1-1 WO-EX 1 SIGU, 7
1270-2 2 X 1-2 WO-EX 2 SIGU, 7
1270-3 3 Y 1-3 WO-EX 3 SIGU, 7
1270-4 4 X 1-4 WO-EX 4 SIGU, 7
1270-5 5 Y 1-5 WO-EX 5 SIGU, 7
1270-6 6 X 1-6 WO-EX 6 SIGU, 7
1270-7 7 Y 1-7 WO-EX 7 SIGU, 7
1270-8 8 X 1-8 WO-EX 8 SIGU, 7
1270-9 9 Y 1-9 WO-EX 9 SIGU, 7
1270-10 10 X 1-10 WO-EX 10 SIGU, 7
1270-11 11 Y 1-11 WO-EX 11 SIGU, 7
1270-12 12 X 1-12 WO-EX 12 SIGU, 7
1270-13 13 Y 1-13 WO-EX 13 SIGU, 7
1270-14 14 X 1-14 WO-EX 14 SIGU, 7
1270-15 15 Y 1-15 WO-EX 15 SIGU, 7
1270-16 16 X 1-16 WO-EX 16 SIGU, 7
1270-17 17 Y 1-17 WO-EX 17 SIGU, 7
1270-18 18 X 1-18 WO-EX 18 SIGU, 7
1270-19 19 Y 1-19 WO-EX 19 SIGU, 7
1270-20 20 X 1-20 WO-EX 20 SIGU, 7
1270-21 21 Y 1-21 WO-EX 21 SIGU, 7
1270-22 22 X 1-22 WO-EX 22 SIGU, 7
1270-23 23 Y 1-23 WO-EX 23 SIGU, 7
1270-24 24 X 1-24 WO-EX 24 SIGU, 7
1270-25 25 Y 1-25 WO-EX 25 SIGU, 7
1270-26 26 X 1-26 WO-EX 26 SIGU, 7
1270-27 27 Y 1-27 WO-EX 27 SIGU, 7
1270-28 28 X 1-28 WO-EX 28 SIGU, 7
1270-29 29 Y 1-29 WO-EX 29 SIGU, 7
1270-30 30 X 1-30 WO-EX 30 SIGU, 7
1270-31 31 Y 1-31 WO-EX 31 SIGU, 7
1313-1 32 Y 1-32 WO-EX 65 SIGU, 8
1313-2 33 X 1-33 WO-EX 66 SIGU, 8
1313-3 34 Y 1-34 WO-EX 67 SIGU, 8
1313-4 35 X 1-35 WO-EX 68 SIGU, 8
1313-5 36 Y 1-36 WO-EX 69 SIGU, 8
1313-6 37 X 1-37 WO-EX 70 SIGU, 8
1313-7 38 Y 1-38 WO-EX 71 SIGU, 8
1313-8 39 X 1-39 WO-EX 72 SIGU, 8
1313-9 40 Y 1-40 WO-EX 73 SIGU, 8
1313-10 41 X 1-41 WO-EX 74 SIGU, 8
1313-11 42 Y 1-42 WO-EX 75 SIGU, 8
1313-12 43 X 1-43 WO-EX 76 SIGU, 8
1313-13 44 Y 1-44 WO-EX 77 SIGU, 8
1313-14 45 X 1-45 WO-EX 78 SIGU, 8
1313-15 46 Y 1-46 WO-EX 79 SIGU, 8
1313-16 47 X 1-47 WO-EX 80 SIGU, 8
1313-17 48 Y 1-48 WO-EX 81 SIGU, 8
1313-18 49 X 1-49 WO-EX 82 SIGU, 8
1313-19 50 Y 1-50 WO-EX 83 SIGU, 8
1313-20 51 X 1-51 WO-EX 84 SIGU, 8
1313-21 52 Y 1-52 WO-EX 85 SIGU, 8
1313-22 53 X 1-53 WO-EX 86 SIGU, 8
1313-23 54 Y 1-54 WO-EX 87 SIGU, 8
1313-24 55 X 1-55 WO-EX 88 SIGU, 8
1313-25 56 Y 1-56 WO-EX 89 SIGU, 8
1313-26 57 X 1-57 WO-EX 90 SIGU, 8
1313-27 58 Y 1-58 WO-EX 91 SIGU, 8
1313-28 59 X 1-59 WO-EX 92 SIGU, 8
1313-29 60 Y 1-60 WO-EX 93 SIGU, 8
1313-30 61 X 1-61 WO-EX 94 SIGU, 8
1313-31 62 Y 1-62 WO-EX 95 SIGU, 8

COMMAND EXECUTED

[zhanglw268]

For Huawei:
1. use "DSP ACIC" to check the CICs status;
2. use "CHK E1T1CRS" to see whether you have cross-wired E1s, please note that this is a service affecting comand when you run on the live network.

Zhanglw268

[justdream]

For Huawei:
1. use "DSP ACIC" to check the CICs status;
2. use "CHK E1T1CRS" to see whether you have cross-wired E1s, please note that this is a service affecting comand when you run on the live network.

Zhanglw268

Dea please explain in details how to perform..
I'm too much interested in learning how to perform it
Thanks

[scorpiobgd]

usefull... thanks.... huawei has a very simple and intuitive commands...

[orcun_laing]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G

Hi,

If your network has never had problem before and problem just started, I would recommend to check alarm history of your voice coding/decoding board. I'm not sure about the board name as it varies for different vendors. Sometime, higher CPU load of the voice coding/decoding board also can cause such problem. If your hardware board is not working properly, calls will become silent after few seconds or minutes talking or silent at first answer straightaway. You should check every aspect of the board to confirm it's not hardware that causes silent calls.

BR///

[aslsh21]

Experts,

I face a problem of getting silent calls from both parties (I mean both the caller and the calling person couldn't hear each other)

Do you know what's the root cause of this problem and how to solve it?

as I face it frequently :(
My network is 2G

the probelm may be :
1- faulty DRI ( HW )
2- bad FREQ ( Change the ARFCN to another one )

[auspicious]

Hi

It can be a case of "CIC Mismatch " (Non - alignement of PCM's on A Interface ) .
Do the CIC Mismatch testing in coordination with Core Guys.

1. Do this activity during Downtime (In night) .
2.Block all the PCM's towards MSS except one and do call testing .
3. Repeat this for all PCM's.
4. The PCM's were you get mute calls are either wrongly mapped 9configuration wise) or wrongly patched at the DDF side.

Br//
Auspicious

[arjaypanganiban]

Hello Justdream,

I assume that your core network is Huawei and also your RAN since you encounter this most of the time. Please fill in the details below so we could isolate your problem later.

What type of transport do you use for A - Interface? Is it E1 or STM1?
Have you checked the mapping of TID assignments both for MSS and MGW?
Have you verified the CIC status both for NSS and BSS side?

[justdream]

Dears,

Are there any row counters could be used as an indicators of cells suffers from Silent calls?

[maahsan]

If this problem happened on a new commisioned BSC, re-homed BSC, BSC on which Ater were added recently than most probable it is caused by CIC mismatch or cross patching on A-interface.

You can ask your NSS team to do a dial test in which they will force call from a certain IMSI to be routed to each E1 on A-interface. That's how they can narrow down which A-link is cross patched or has CIC mismatch. You won't have access to core network to do it on your own.

[Md.Moniruzzaman]

We faced this same problem while working in Grameenphone network.
Vendor was Huawei. The problem was in the TRFO node.
The problem occur while speech coding trying to change from AMR to Non-AMR

[almoqbali36]

we have same issue in our network but the vendor is ******** and switch is huawei, the problem not always some times we did trace for the calls but nothing appear.
and I have one intresting senario which i did during the drive test:-

"during my drive test I make a call and it has silent call and then I hold the call and make another call. B number answer the call it was fine not silent call then I tried to join the two calls but they droped both"

[khalidsaif82@gmail.com]

it is related to CIC


please perform CIC test between msc and trc

please check if there is any blocked Devices .

[zloy_qwer]

Also you can check statistic with CIC usage.