Dear Experts
How do you observe VoLTE mute in your networks? in the absense of probe?
Without probes you must really on KPIs and/or DT data.
Hello @ravinder.
Mute calls are a not so common in an optimized network, however they could occur due to different reasons (very bad radio conditions, CORE issues, bad routing configuration on Tx path, etc). If you have Drive Test available with MOS (Mean Opinion Score) you can see areas with very low MOS (lower than 3 or 2) and there you can find areas suceptible to Mute calls on VoLTE.
Other way using KPIs/KQIs, try to use indicators / Counters related to radio conditions, for instance: find areas with very poor SINR on PUCCH/PUSCH to get an idea of areas with bad quality conditions or use the Aggregation 8 level on PDCCH (in poor radio conditions an UE will require 8 CCEs for each PDCCH transmision) .
Regards.
JS.
Hello @ravinder
Every vendor comes up with some counters to identify the mute calls(Audit Gaps). If you please specify the vendor. I may be able to help you with the relevant counters. Thanks!
P-CSCF SBC KPI can help
During VoLTE Mute call RTP packet bytes gone to 0.
If it continues for RTP timeout timer, then VoLTE call drop as well, and UE will send bye.
Mute call mainly due to poor RF but I don’t think there any way to handle it.
Most of vendors don’t have counters to check mute call.
Yes, they exist, and are called Audio gap counters.
As per @Mustafa_Rawat replie too.
I know in Nokia these counters are there.
Good to know, maybe in new release available. 
Voice Measurement and Analysis (VoMA) Samsung uses this for detecting RTP packets with delay greater than 400 ms to count for mute call.
Samsung experts may elaborate.
Is it using probes over Core network or is it Samsung tool or counter?
It is some licensed counter, I think.
You can easily detect those with proper RLF timers and constants, but you can’t fix it.
Yes agree we can’t fix, but can lower percentage of Mute Call, which customer love to see.
Most of the mute calls happens during HO.
Also due to poor RF, meaning low SINR.
There is no remedy for mute call but for VoLTE I find if we improve UL KPI like PUSCH, SINR, UE PHR, UL BLER there will be big relief.
For this we need to reduce overlapping.
Yes low sinr as well leading to dl RTP bytes 0.
Note: There is one very good tool developed by Alcatel Lucent guys named eDAT, I find that tool very useful during VoLTE analysis.
Also due to poor Uplink.
Total 22 counters are there.
These are uplink and same 11 for DL also, you can check with LTE 3443 feature in detail.
SRAN19 onwards available.
UL_VB_PERIOD_BIN1
UL_VB_PERIOD_BIN2
UL_VB_PERIOD_BIN3
…
UL_VB_PERIOD_BIN9
UL_VB_PERIOD_BIN10
UL_VB_PERIOD_BIN11
* VB means voice break.
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Hi experts, I have customer complaints for VoLTE mute calls but from the DT logs nothing indicates mute calls: rf good, no RLF, no rlc retransmissions, I can see RTP packet without packet interruption time until Sip Buy msg with cause “RTP timeout”.
Anyone has idea what could be checked more?
From Annova tool you can check.
Main funda check for tdiscard timer value for qci1 increase it if it lower side make it 300ms.