There is 1 certificate that covers *.nexmo.com when using our API. This is signed by a major Certificate Authority. If you do not trust the major Certificate Authority by default, this must be imported (note that this is very unusual).
The certificate can be downloaded from:
Please note we can switch host IP addresses at anytime and without notice to insure high availability and transparent failover if needed.
This single certificate is in use instead of the former use of 2 certificates prior to 2nd December 2015.