First, I know that Grandstream is no longer supported. However, I have a legacy client with about 100 GS 2130's and GS 2160's that has decided to keep those, even if it means staying on an older version of 3CX. I have them working fine in my lab on V15, including software upgrades, park, etc. Only issue so far is some of the CTI features which the client does not use. I would like to know if anyone has upgraded a production environment to V15 using these GS phones and if so how it is working out. Any info is appreciated.