I’ve been fighting a problem for a long time and being at my wits end I’d like to ask for your help.
The problem is as follows:
I have a 5G NSA test/research network setup with a Samsung S21 as a test device. Everything is working fine when I use the USIM provided by the vendor of the 5G network (UE attaches to the gNB for data), but when I try a different USIM, provided by Sysmocom, the UE does not even report that it is capable of EN-DC. The NAS Attach message is missing the additional UE network capabilities flags and the additional UE security , it’s not just that the DCNR bit is not set.
I have tried to make the USIMs equal in term of services, PLMN and access technology settings, different band of LTE/NR, etc. to no avail. It is as if the UE is behaving as a before Release 14 device with the Sysmocom USIM.
One major difference between the two USIMs is that the Sysmocom has ISIM application and the UE operation mode is ‘normal’, while the other does not.
I’d be much obliged if anyone can give me an advice/hint/lead.