Online Certificate Status Protocol (OCSP) is used to check the certificate revocation status of an x509 certificate in use. The phone needs to trust the OCSP server and its CA certificates must be installed on the phone. These certificates are called OCSP Trust Certificates.

OCSP Trust Certificates are installed in the same way as those for System Manager. However, OCSP Trust Certificates use a different parameter name called OCSP_TRUSTCERTS. This parameter follows the same format as that for TRUSTCERTS.