You can export the existing certificate installed on the Sonus SBA at anytime by following these simple steps:
You are able to export a PKCS12 Certificate and Key as follows:
In the left navigation pane, under Lync™ Survivable Branch Appliance, click SBA Certificate.
From the Action drop down list, select Export PKCS12 Certificate and Key.
In the Password box, enter the password. See Importing an SBA Certificate.
The password is user generated/supplied. This will be required when Importing an SBA Certificate for this certificate on another node.
Click OK.