activate.3cx.com is current. Are you on an old version of 3CX? I believe it was 18u2 that was required and that was a while ago.
Edit: the email:
“To improve our cloud services, the FQDN endpoint used to activate 3CX products will change to
activate.3cx.com. The current activation endpoint will be terminated, the
latestby 28th February 2022.
What do I have to do?
Review your network access rules and ensure that you allow connectivity to
activate.3cx.com. Outbound TCP:443 must be allowed to
activate.3cx.com. Due to the nature of our service clusters, we cannot provide you with a fixed IP list.
Ensure that you update your 3CX PBX by the 28th February 2022 to v18 Update 2. Alternatively ensure that version 16 Update 8a is installed, however this will be a short-term fix - until November 2022.
Upgrade to v18 to ensure long term support, compatibility and security. If you require assistance please contact a local
3CX Partner or ask the 3CX Community
Forums.
Best regards,
The 3CX Team”