Voice mail services
Voice mailboxes are generally included in mobile subscriptions and available, increasingly free of charge, as a calling feature for fixed line subscriptions. Revenues for voice mail services come from subscriptions, e.g. monthly subscription for the service, direct call back from voice messages, extended storage capacities or additional voice mailboxes for phone extensions, and from the traffic revenues generated by these services, typically listening to voice mail or recording messages. As shown in Fig. 1, in Europe, mobile voice mail generated over 60% of voice mail revenues in 2005. In 2010, mobile voice mail should still be the most important revenue stream, with almost 55% of the total revenues, but unified voice mail should gain in importance, generating over 20% of voice mail revenues.