In what situation UE can have 2 Default Bearers?

Hi All,
For LTE, in what situation UE can have 2 default bearers? Apart from VoLTE call where 2 default bearer seen with qci9, qci5.
Any other scenario possible in LTE?


If you have more than 1 APN. Each APN has a default bearer.

For VoLTE, although we don’t see it in available APN list on handset but from core perspective, mobile is connected to 2 different APNs and hence we have 2 default bearers.

Yes, for VoLTE we can see 2 APN indicates 2 default bearer.

Need to understand any other scenario possible for LTE having 2 default bearer.

We were working on 4G Emergency Network, which was another APN.
So we had 3 default bearers.
Likewise if you have specific APN created by MNO like gaming or streaming, it will have its own bearer.

Yes good idea, thanks! :+1:
What APN used for emergency call? Is it like SOS?

No it was called something else.
4G Emergency Network is different than SOS/999/911 calls.
Its for first responders.

Every QCI will require separate bearer.
If it’s for GBR then dedicated and if for NGbR then default.
Depending upon how many services you are using at a time.

Operator may configure more than 2 APNs based on type of services.
APN is used to identify PDN network and in current scenario either user have data service or voice over PS that is VoLTE and so only two APNs.

1 Like

Yes thanks! :+1:
Now as mentioned (@ran_core_consultant) with emergency there are 3 as well.

Please remember for default bearer only we need APN.
Dedicated bearer always linked with default bearer.

Yes, aware about it.
Final count ends as I stated. If any correction then please mention.

I think encryption is kept as null instead of SNOw3g for SOS calls.

I’m not sure if it has to be kept null, but it definitely can and tests we do are on this way.