Question about 5G NSA:
Let us say that we have a 5G capable UE, in a 5G capable network but SIM card is not provisioned for 5G.
Will the DCNR bit inside attach request be set to 1 or to zero?
Or where the call flow for 5G will stop?
Why UE will not get 5G services according to this call flow: https://www.eventhelix.com/5G/non-standalone-access-en-dc/en-dc-secondary-node-addition.pdf ?
When you say SIM not provisioned, does that mean no EF file related to 5G or subscription related limitation?
Cases:
If network nodes (MME) supports 5G but just in HSS subscriber hasn’t 5G subscription, at attach request UE put DCNR supported and after MME send ULR to HSS and at ULA, NR as secondary RAT was not allowed, at create session request, MME doesn’t put DCNR flag.
But if MME doesn’t support 5G, after a few times attach, UE finds that network doesn’t support 5G and UE also doesn’t put “DCNR supported” in attach request.
At Samsung UEs, usually DCNR_RESTRICTION shows that network supports 5G or not.
If this value be true, UE doesn’t put DCNR flag in attach request based on my experience.
But dcnr bit is about UE not about network.
Then again if no 5G provisioned on sim card/nas will dcnr in attach request be zero or one?
Yes, but in attach accept seems can be a flag that shows network capability then that parameter will be TRUE.
About subscription, because UE isn’t aware, put that as supported.
Do you know the name of that param in attach accept?
This IE “Use of dual connectivity with NR is restricted” in EPS network feature support IE of the Attach Accept/Tracking Area Update Accept message.
Also if UE hasn’t subscription in HSS for second time that wants to send attach request, seems should change flag to 0 because at previous attach, it found that.
I couldn’t find it in attach accept message.
Seems it depends on MME configuration and vendor.
But there is such flag that UE can find something about DCNR capability of network or even subscription in HSS.
Just want to add the information.
I have found the same case for this and as per traces the process will be stop post first attach request verification, in this point Core will inform UE that EPS network feature RestrictDCNR bit to “use of dual connectivity with NR is restricted”
2nd related DCNR. In this case DCNR should be mentioned as “1” bit , please noted some mobile sent bit 1 but some mobile 5G supported doesn’t provided the DCNR bit clearly but it represented under octet 9 information as long as octet 9 was sent from UE to NW so NW able to identified that handset supported the 5G tech.(it was tested on ZTE mobile)
Basically Octet 9 always broadcasted under 5G handset information, we can see from Xcap analyses,
Normal octet 9 information. With or without bit 5 it doesn’t have any issue.
Bit 1- Multiple DRB
Bit 2- V2X PC5
Bit 3- RestrictEC
Bit 4- CP Backoff
Bit 5 - DCNR
Bit 6- N1 mode
Bit 7- SCG
Bit 8- 15 bearers.
So don’t confused if DCNR is not available but while octet 9 is available so we can said that mobile is 5G capable here.
Process stop on this step while 5G is not provisioned.
It is attach accept that informs if dc will be used or not.
Dc will restricted as per the case.
Yes, i saw this in another UE another SIM (not the one without 5G services).
Ok. So it means this SIM is normal right?
And able to have 5G services here.
Or this SIM still without 5G provisioned?
When SIM is not provisioned for 5G in attach accept dcnr will be: restricted.
Nice so its cleared. 
