Hi,
yes I have some updates. I tested with two different timeslot configurations: CCCH+SDCCH4+CBCH on ts0 and SDCCH8+CBCH on ts1. In both cases I'm using an iPhone8 to test. With the first ts configuration, the iphone could not perform the location update procedure, so basically I had no connectivity to the basestation. With the second, the location update procedure goes through, I'm connected, I can send/receive sms and phonecalls, but smscb are not being delivered, at least that's what I think. I can definitely see the smscb messages on the gsmtap interface and I can see the smscb request coming from RSL link. However, I don't get any broadcasts on the phone itself. But this last part is till not very clear, I need to investigate a bit more on what's going on. As a side note, when using CCCH+SDCCH4+CBCH ts0 configuration, both my iPhone8 and my Huawei Honor9 cannot perform the location update procedure. Apparently they can only get the BCCH channel but the location update procedure never starts.
Let me know if this helps and what kind of debug I can provide you, as you may guess getting debug out of mainstream smartphones is not really easy, so what I can do is limited on that side.
Thanks!
Lorenzo