1. Install WebAPI by Creomate
2. Create Externsiob https://{{3CXFQDN}}/webapi/{{AccessKey}}/ext.new?num=300&authid=300&authpass=300
3. Or update extension https://{{3CXFQDN}}/webapi/{{AccessKey}}/ext.update?num=300&authid=300&authpass=300
4. Use it as usual
5. Don't use on public Internet

Disclaimer: This life hack is provided “as is”. Use it solely at your own risk.