SIP message 401 unauthorized, call drop event

Umar_Mir · April 20, 2020, 3:00am

Hi Experts.
Please help analyse SIP message 401 unauthorized, call drop event occurred here.

Spale · June 16, 2020, 12:35pm

Check what happened on RRC why you deregister.
401 Unauthorised is normal behavior after Register.

Umar_Mir · June 16, 2020, 12:36pm

Before RRC reconfig no EPS bearer identity assign in ESM response.

Spale · June 16, 2020, 12:37pm

You had RRCConnectionRelease message on top.
Check whay that happened before.
After that RRCConnectionReconfiguration message whith reconfigured DRBs came after your selected message.

Umar_Mir · June 16, 2020, 12:37pm

There is not rrcconnectionRelease before ESM response.
Which message you refer to?

Spale · June 16, 2020, 12:38pm

Second row.

Aztel · June 16, 2020, 12:39pm

Please check whether Dynamic QoS Modification (E//) or eRAB Modification (N//) is activated/not.

jshpriyank · June 16, 2020, 3:45pm

401 unauthorised is a normal msg during call flow for authorization…check 503 service seems ue is not able to perform requested service. Also ue was deregistered as mentioned by Spale.

Umar_Mir · June 17, 2020, 5:32pm

I can’t see any other abnormal event but IMS voice server de registered abnormally. Also HHO intrafreq occur to a logical cell b4 rrc connection rel.

Umar_Mir · June 17, 2020, 5:33pm

What is recommendation for Huawei?

Also: I have all drops on this one location with multiple attempt failures.

Spale · June 17, 2020, 5:35pm

With RRcconnRelease (probably due to radio or problem with HO) all 3 bearers are released.
UE goes to idle and do again RRC establishment.
After that need RRCConnReconfiguration to do reactivation of all 3 bearers.
Check radio conditions before Rrc release message.
And maybe you will need to check S1AP interface from eNB side. Those consecutive drops looks suspicious.

mohit_lohani · June 17, 2020, 5:37pm

Any inputs on

Affected QCI
KPI Counter which is affected

Jorge_Zambrano · June 17, 2020, 5:38pm

Interference?

RMatolia · June 17, 2020, 5:39pm

Looks like call failed at 503 Unavailable.

Spale · June 17, 2020, 5:40pm

SIP IMS Call flow:

Usman · June 17, 2020, 5:41pm

Seems SIP/IMS signalling is successful.
The issue is voice bearer couldn’t be allocated as RRC reconfiguration message is missing (to update default radio bearer to voice bearer) in L3 as per shared snap.
In general multiple reasons can be… unsupported encryption algorithm/voice codec causing de-registration, some underlying enb level parameter is missing if it’s not NW level issue, Bad Coverage (levels, quality), choked capacity, TNL failures, S1 Interface failure, etc.

Umar_Mir · June 17, 2020, 5:42pm

RF environment doesn’t look bad for consecutive drops.

Umar_Mir · June 17, 2020, 5:43pm

I didn’t get this message after 401 unauthorized.

Spale · June 17, 2020, 5:45pm

RSRP is ok but check RSRQ.

Spale · June 17, 2020, 5:46pm

Chek again your first photo.
After 401 you will see UL Register and 200 ok on DL → successfully registration.