NEC SL2100 lacks call recording feature, CRM integration and overall very complex system to learn, there are no training material or tutorials out there. Programming interface is not intuitive at all, there are literally hundreds of proprietary settings without any explanation in manuals. Sl2100 was planned as more affordable small system to be sold by resellers of SV9100 enterprise grade system. So called tech support portal NTAC was never open to resellers of SL2100 series. Another main disadvantage of sl2100 is confusing and slow licensing scheme, it takes 3-5 days to get a license for a feature you want.
Nevertheless, their hardware is rock solid. I have many PBXs running for 10+ years with 100% uptime. If there are no requirements for anything more than calls, greetings voice and intercom, they are superior systems.
Again, due to them leaving US market, I’m planning on slowly introducing Freepbx solutions. I’m leaning towards on premises setups just because it’s easier to manage for me. At most locations I also provide and manage network infrastructure with cellular wan failover in place, as well as linksys or grandsteam fxs to a different sip provider as backup. All locations prewired for VoIP phones with Poe switches in most, so switching over wouldn’t take long. I can have both phones on the desk to make it easier for customers to transition