We will be updating the Zoom Phone platform to use a Trusted Public Certificate Authority. This change will take affect for users based in the Asia Pacific region/SIP zone on February 27, 2021 and will be implemented for other regions at a later date.
Zoom Phone admins should ensure that they have updated their public certificates on their devices and carrier if needed. Zoom Phone users must be on Zoom desktop client or Zoom desktop app 5.0.5 or later for full functionality.
For more information, please see: https://support.zoom.us/hc/en-us/articles/360056087612-Zoom-Phone-certificate-update