Hi, I'm looking for some support on solving our current 3CX issue. We are an affiliate level partner and 3CX is a small part of our business. We have used 3CX for nearly 10 years now without many issues. Our instance is hosted at IONOS along with a dozen customers running similiar 3CX instances . None of our customers have any issues and the only change we've made lately was to upgrade to v18 (which we've done across the board to all our customers instances). The situation is that none of the desk phones in the office or at home work properly i.e they don't ring and you can't hear audio if you try to make a call. However, we've found that the mobile phone 3CX App appears to work fine (using office wifi) so we're getting by with that for now. The firewall check on the 3CX system passes just fine. With 3CX being a small part of our business and it rarely ever going wrong we don't tend to keep up with the skills required to delve into things when it does go wrong. I want to know who's best to contact for support in this situation. Our phones are Yealink which show up as unsupported (but that should not stop them working) and our SIP provider is SureVOIP/Suretec (again unsupported but worked fine before). I was reluctant to open a paid for support ticket from 3CX as they state they won't entertain unsupported phones and providers. Thing is we have a dozen custers using 3CX with unsupported phones and the same unsupported provider which are running perfrectly fine. Any advice would be much appreciated 
