While it is possible to build a Microsoft unified communications infrastructure using only private certificates generated internally, it greatly handicaps the effectiveness of the UC environment. In order to communicate with devices connected outside of the network- including laptops of employees in hotels or coffee shops, or mobile phones, as well as the ability to connect with vendors, customers, or partners- a 3rd-party trusted certificate is necessary.
Certificates are sold with expiration dates and must be renewed, which adds some administrative overhead. Someone has to track and monitor certificate expirations and make sure new certificates are purchase so that the unified communications network does not experience an interruption as a result of an expired certificate. Comodo has rolled out a new offering with a 3-year expiration that is also customized to deliver security benefits customized to the Microsoft Unified Communications environment.
According to this article, Comodo’s Microsoft UC certificates “enable administrative flexibility to secure client-server and server-server communications while supporting multiple Exchange and Office Communications 2007 services (e.g. Outlook Web Access, SMTP-TLS, Auto-Discovery, ActiveSync and Outlook Anywhere) – all with a single UC Certificate.”