It is shameful how they treat their most successful product lines like red headed stepchildren.
Its all about economics...LG discontinued the XTS hardware platform worldwide due to its cost to produce. The SBX, MBX and its LG counterparts are cheaper to market because one box tries to fit all (not always so good in my opinion...like putting a size 10 foot in a size 9 shoe) but that is the concept. Vertical is now charging for XTS phone support in part to encourage dealers to move to the current lines sooner than later and they are far from the only tech company to charge for incidents. Intuit comes to mind.
What I don't like is Vertical not providing extensive (like the XTS) documentation for any current system thus making us search around in the dark for answers to questions about basic features that phone systems have had for years. I really don't like calling tech support to ask about station group overflow or other questions where I end up saying "the XTS can do this...but how does the ?BX handle this?"....only to be told "Well this isn't an XTS" like I didn't know that already. Explain to me what the ?BX will do in a PDF file with a decent complete index and I won't have to call tech support so much.....is that so unreasonable?
I have learned more about the SBX from reading IPLDk-60 documentation than from the SBX documentation itself. There is a caveat to that, not all functions operate the same or even exist in both systems due to the Vertical tweaks to the operating system.