# Certificate Authority Trust

The Certificate Authority (CA) Trust tab allows the administrator to upload additional root CA certificates, in PEM format, to be added to the list of trusted CA certificates on MSL.

Some customers have their own enterprise root CA certificates, used to sign the certificate that will be installed on the MSL web server. To install a certificate signed by an untrusted CA, the root CA certificate must first be uploaded to and trusted by the server.

To upload a new root CA certificate to the CA trust bundle:

1. In the Certificate Authority Trust tab, click Choose File.

2. Browse to the location of the certificate, and click Open.

   Note: The certificate must be in PEM format.

3. Click Install Root CA Certificate.

By default, the following two Mitel root CA certificates are added to the Trust Store. These are visible in the Certificate Authority Trust tab.

- The legacy root CA certificate is named Mitel Networks Root CA. This is used to complete a full chain of trust between Mitel legacy equipment and applications such as MBG.

- The new Mitel root CA certificate is named Mitel Products Root CA and will be used in new products going forward.