Silent calls

[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: