Regarding change of GBR and MBR

[Shreyas-B-Aradhya]

Hi, I wanted to know if there is a way reduce the GBR and MBR for audio and video?

loopback_logs_19122025_3.zip

Regards,
Shreyas

[herlesupreeth]

Can you try changing the values in open5gs webui for QCI 1 and QCI 2 PCC rules and see whether they have any effect?

[Shreyas-B-Aradhya]

Hi supreeth, I have changed from 128kbps to 100 kbps in both the ue's but it is not working


Below are the loopback logs:
loopback_logs_22122025_1.zip

[herlesupreeth]

Try changing the bitrate in the P-CSCF configuration file.

i mean the following parameters

• rs_default_bandwidth integer
• rr_default_bandwidth integer

in ims_qos module settings.

more info here - https://www.kamailio.org/docs/modules/6.1.x/modules/ims_qos.html#id1368

[Shreyas-B-Aradhya]

Hi @herlesupreeth , sorry for the delayed response..I tried the changes in kamailio_pcscf.cfg shown below

when I checked in the INVITE packet for both volte and vilte , there was no difference seen in the rr and rs bandwidth
For vilte

For volte

Below is the loopback logs for the same
loopback_logs_06012026_rrandrs_1.zip

[herlesupreeth]

@Shreyas-B-Aradhya Rather than checking the SDP of INVITE, with the changes in kamailio_pcscf.cfg you should observe the change in the Rx AAR message because its a modification done on the PCSCF and not on the UE.

I had a look at the pcap and I see that the changes done to PCSCF is not taking in to effect (for RS and RR value). But, I see that in Rx AAR from PCSCF to PCRF the value used for GBR and MBR is taken from the following value x 2 in SDP (sent by UE)

For Audio:

Bandwidth Information (b): AS:41
    Bandwidth Modifier: AS [Application Specific (RTP session bandwidth)]
    Bandwidth Value: 41 kb/s

For Video:

Bandwidth Information (b): AS:384
    Bandwidth Modifier: AS [Application Specific (RTP session bandwidth)]
    Bandwidth Value: 384 kb/s

In E-RAB Setup for Audio:

gbrQosInformation
    e-RAB-MaximumBitrateDL: 82000bits/s
    e-RAB-MaximumBitrateUL: 82000bits/s
    e-RAB-GuaranteedBitrateDL: 82000bits/s
    e-RAB-GuaranteedBitrateUL: 82000bits/s

In E-RAB Setup for Video:

gbrQosInformation
    e-RAB-MaximumBitrateDL: 768000bits/s
    e-RAB-MaximumBitrateUL: 768000bits/s
    e-RAB-GuaranteedBitrateDL: 768000bits/s
    e-RAB-GuaranteedBitrateUL: 768000bits/s

I have to read the specification why the value (in SDP) x 2 is considered in open5gs rather than just value.

Also, if you want to change the value of GBR and MBR its better to change the setting (AS value) in Samsung IMS secret menu

[Shreyas-B-Aradhya]

ok thanks @herlesupreeth , will try in that itself.