Dear VoLTE Experts,
Is anyone aware of how SIP drop call rate is calculated?
Anyone have call flow of it?
Is it related to drop call at setup time i.e. from invite to 180 ringing suddenly UE gone for SRVCC.
Usually once RTP packet flow started drop call seen due to flow stop or UE lost.
SIP reason drop I need to check is something related to bye message send by UE due to RTP timeout one of reason I seen.
RTP timer configured in ims node value 20 ms if no RTP flow during that time then Ue send bye.
Thanks, I am aware of this, but I am looking for SIP call drop, maybe new kpi.
We have to improve it, but no idea at all how it is pegged, how to analyse the degradation.
It is substitute to VoLTE drop rate.
What all SIP message there?
Is it 4xx or 5xx?
SIP drop rate is IMS own drop.
There are number of reasons which could contribute (high error rate, no RTP flow, signaling issue).
Its worth checking your vendor’s product documentation, they must have some formula defined.
I assume you are taking about QCI-5 Drop Call Rate.
If yes you will have counters for QCI-5 like the way you calculate for QCI-1.
Thanks.
Do you have any rough call flow, or some more detail reason for SIP drop or troubleshooting gudeline?
Basically, i want to know is there any direct relation of ERAB drop rate QCI-1 with SIP drop.
Since it is calculated at IMS, it won’t have counters at eNB level.
There is.
SIP signaling flows on Qci5, if the bearer drop or SIP signaling drops, your call will drop (Qci-1 drop).
Check also this: IP Multimedia Subsystem (IMS) Call Flows
(Also in our Community Favorites)
If you have Ericsson we can easily calculate.
For sure IMS will have there own way of calculation.
It is Samsung.
It have standard call flows, but not for SIP drop call. 
Are you sure RTP flow timer is 20 msec? Maybe 2 seconds
There are many cases of RTP packets missing for 40-80 msec and still VoLTE is not released.
There is chance you have high packet loss issues.
It’s 20/30 second. Not Milliseconds.
No RTP timer i am talking about.
Are you talking about No RTP timer in IMS?
If yes then it is always in seconds. If it had been in millisec then there would have no mute call and and calls with no RTP would have dropped.
If there is no RTP packet for No RTP timer time in downlink then UE sent BYE
This timer (RTP timer in IMS) is usually 15 -20 seconds.
I faced it when no RLF was triggered but call was muted for 15 seconds before call was released.
Even user cannot disconnect call.
I seen many issue due to this timer.
In VoLTE.
There are few tools which show RTP packet bytes in DL/UL.
If value 0 for timer timeout then ue send bye.
But it is 15-20 seconds not mseconds.
Can be set to 2 seconds but usually networks use 15-20 seconds.
Because nobody wants drops for VoLTE.
Everybody wants to drag teh call in poor rf rather then realease it and pegg a drop.
Correct. I have seen such release on field many times. For JIO its was 25 earlier.
Now its 20 second.
Phone was so dizzy for 15 seconds that you cannot even release the call manually.
I admit it was poor RF.