Missed calls go to enterprise voicemail. Voicemail is a popular feature of mobile phones partly because users like it and partly because mobile operators like it. Users get personalized messages but they use up their minutes to check messages and to listen to them. However, in a mobile UC implementation, calls to the mobile device are frequently business calls placed to the enterprise and therefore should, for security and information integrity reasons, be processed by the enterprise voicemail service and not by the mobile operator's service.

With the recent requirement to surrender copies of both voicemail messages and email messages to the plaintiffs attorneys in the event of legal proceedings, it is important to drive all business voice messages into the business voicemail infrastructure where message date-time stamps and other appropriate storage practices can implemented. Engaging mobile operators with these standards are quite onerous and definitely outside the scope of the typical user service agreement.