# Other Classes of Service - Overview

A class of service differentiates privileges and functions for mailboxes. The previous section discusses the Features Class of Service (FCOS), which controls the features in mailboxes. This section discusses three other classes of service:

- Limits Class of Service (LCOS) controls time and storage parameters within mailboxes, such as the number of messages the mailbox can store, as well as the set of Prompts

- Group Class of Service (GCOS) manages communication between mailboxes

- Restriction Class of Service (RCOS) controls the outdial applications, such as Call Placement, message delivery, and pages, and limits these telephone calls by either area code or prefix.

The two remaining classes of service are described in detail outside of this section:

- A Network Class of Service (NCOS) controls network access for users; see the NP Net application section.

- A Tenant Class of Service (TCOS) manages mailbox interaction between user communities; see "ESMDI Integration" in the NuPoint Unified Messaging Optional Integrations Guide for more information.