Installation using OCS 2007 Certificate Wizard

• Open the ZIP file containing your certificate.
• Copy your_domain_name.cer the Office Communications Server where you you generated the CSR.
• On the server click Start, then Programs, then Administrative Tools, and then click Office Communications Server 2007.
• Expand the snap-in until you find the Enterprise Edition Server.
• Right click on the Office Communications Server where the CSR was generated previously, and click Certificates.
• Click 'Next', then chose to 'Process the pending request and install the certificate'.
• Browse to your_domain_name.cer and click Next.
• This will install the certificate.
• You can view the certificate and close the certificate wizard.

Your SSL Certificate is now installed and ready to use.

For more information, see Microsoft's official Office Communications Server documentation