Hello, experts.
I’m experiencing issues connecting an iPhone to 5G in an NSA network.
Interestingly, Redmi and Honor devices connect to 5G without any problems, but the iPhone doesn’t.
From the traces, it appears that the network is not requesting NR information from the UE, so the UE isn’t reporting its NR capabilities.
The iPhone indicates that the issue lies with the network.
What would you suggest I check to resolve this?
Is this specific to a particular model, or does it apply to all models?
iPhone 15.
I would recommend reaching out to the Core team.
The Core team shared the traces with me, and I opened them in Wireshark, but I’m unsure what to look for.
They should include their comments along with these traces.
If only I had good Core support 
.
First, check in the Attach Request or TAU Request to see if DCNR (Dual Connectivity with NR) is supported:
Also, check the SIB2 message in LTE to verify if the Upper Layer Indicator (ULI) is set to true:
Does this information come from the Core?
No, this information is not from the Core. These details are derived from the RAN (Radio Access Network) side, specifically from the signaling messages exchanged between the UE (User Equipment) and the eNodeB during the initial access and configuration phases.
This information comes from a TAU Request or Attach Request sent by the UE in the Uplink.
The issue occurs only with the iPhone. Other phones work fine, so the configuration should be correct.
Yes, sorry, I didn’t consider that. However, different phones may behave differently if the Upper Layer Indicator is missing.
Right.
Thank you, I saw the message. What could be the reason the iPhone isn’t connecting to NR?
After this, the network does not request the NR information from the iPhone.
