Deployment Guide Polycom CX700
Making the Root CA Certificate Available to a Polycom CX700 Phone
Communication between the Polycom CX700 phone and Microsoft Office Communications Server 2007 R2 is by default encrypted using TLS and SRTP. Therefore, the device needs to trust certificates presented by Microsoft Office Communications Server 2007 R2 servers. If the servers use public certificates, they will most like be automatically trusted by the phone, since it contains the same list of trusted certificate authorities (CAs) as Windows CE. However, since most Microsoft Office Communications Server 2007 R2 deployments use internal certificates for the internal Microsoft Office Communications Server 2007 R2 server roles, there is a need to install the Root CA certificate from the internal CA to the phone. It is not possible to manually install the Root CA certificate on the phone, so it needs to come via the network.
The Polycom CX700 phone is able to download the certificate using two methods:
•The device will search for AD objects of category certificationAuthority. If the search returns any objects, it will use the attribute caCertificate. That attribute is assumed to hold the certificate and the device will install the certificate. To get the Root CA certificate placed in the caCertificate attribute, use the command certutil
.cer file> RootCA. This command will publish the certificate as required by Polycom CX700 phone.
•If the search for AD objects of category certificationAuthority does not return any or if the objects have empty caCertificate attributes, the phone will search for AD objects of category pKIEnrollmentService in the configuration naming context. Such objects exists if Certificate AutoEnrollment has been enabled in Active Directory. If the search returns any objects, it will use the dNSHostName attribute returned to reference the CA and it will then use the Web interface of the Microsoft Certificates Service to retrieve the Root CA certificate using the HTTP GET command http://<dNSHostname>/certsrv/certnew.p7b?ReqID=CACert&Renewa
If neither of these methods succeeds, the error message “Cannot validate server certificate” appears on the screen and the user will not be able to use the phone.
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