Open Zoiper 5, go to Settings > About > Activate , and paste your key into the field. Troubleshooting Activation Issues
If you’re looking for a legitimate review of as a VoIP softphone (its features, call quality, UI, compatibility with SIP/IAX, etc.), I’d be happy to help with that. Just let me know, and I can produce a detailed, fair, and useful review based on official sources and common user experiences. zoiper 5 pro activation key