# About Class of Service (COS)

Class of Service (COS) determines the characteristics that a mailbox will have. Some COS values determine what features will apply (such as x, or x). Other COS values determine what limits will apply (such as x and x). The NuPoint UM system is equipped with a set of default COS values which you can apply to the mailboxes you create. You can also copy and modify the default values to create your own custom COS values.

## Types of COS

- A Feature Class of Service (FCOS) is a collection of mailbox features, options, and abilities, identified by feature bits. For example, a mailbox that has a COS containing feature bit 043 allows that mailbox to receive the message of the day (an announcement from the attendant’s mailbox). each mailbox must be assigned an FCOS. If one is not specifically assigned, then the default FCOS 1 is applied.

- A Limits Class of Service (LCOS) is a group of mailbox limits used to control time and storage parameters within mailboxes, such as the number of messages the mailbox can store. The LCOS also determines the mailbox prompts language.

- A Group Class of Service (GCOS) manages communication between mailboxes for a particular set of users (for example, when some users need to exchange messages with each other but not with the majority of other mailbox owners).

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

Two remaining classes of service are described in detail in other guides:

- A Network Class of Service (NCOS) controls network access for users; see the NuPoint 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.