The activation key is a unique set of credentials (typically your email address and an automatically generated password) sent via email after a one-time purchase from the Zoiper webshop . Activating the PRO license unlocks advanced business functionalities that are not available in the free version. Key Features of Zoiper 5 PRO
Ensure your firewall isn't blocking Zoiper’s outgoing traffic on port 443. zoiper 5 pro activation key