Microsoft Office Communications Server 2007 R2 imposes the following presence policies on users and applications.

Policy name	Description	Maximum number of category subscriptions	Maximum number of prompted subscribers
“Default Policy” (the default presence policy)	A typical user.	1000	200
“Service: Medium” (note the space after ‘:’)	An application that requires additional categorySubscriptions, and is not intended to handle “PromptedSubscriber” prompts.	3000	0 (disabled)

Note:
The categorySubscriptionsvalue is set in a policy and can have any value from 0 through 3000. After being set, a given value, such as 1000, represents the maximum number of category subscriptions for a given user, but has no effect on applications. The maximum number of category subscriptions for an application is 3000. Office Communications Server provides scripts that can be used to create, edit, or delete presence policies, and to assign presence policy for users.

Note:

The categorySubscriptionsvalue is set in a policy and can have any value from 0 through 3000. After being set, a given value, such as 1000, represents the maximum number of category subscriptions for a given user, but has no effect on applications. The maximum number of category subscriptions for an application is 3000.

Office Communications Server provides scripts that can be used to create, edit, or delete presence policies, and to assign presence policy for users.

Presence Policy Fields

The fields that can be used in a presence policy control the number of categories a user can subscribe to and the number of subscription prompts that are received.

CategorySubscriptions Field

XML Name: CategorySubscriptions
Display Name: “Maximum Number of Subscriber Category Subscriptions”
Type: Integer
Valid Values: 0 through 3000

A value of 0 indicates that a presentity cannot make persistent subscriptions.
Client/Server Usage

Client: No action, but an error is generated if the limit is exceeded.

Server: The limit is enforced.

Assuming that a user is subscribed to on five categories ( contactCard, calendarData, note, state, and services), the CategorySubscriptionsvalue limits the number of presentities that can be subscribed to by a user to 200 (= 1,000/5). The client can choose to limit the number of categories it wants to subscribe to for a user by supplying a filter through the RemotePresence.PresenceSubscriptionCategoriesproperty.

If the limit is exceeded (Error 413: Quota exceeded), the recommendation is to switch to polled subscriptions instead of using persistent subscriptions.

PromptedSubscribers Field

XML Name: PromptedSubscribers
Display Name: “Maximum Number of Presence Alerts”
Type: Integer or Token
Valid Values: 0 through 500

A value of 0 means that presence alerts will be disabled.
Client/Server Usage

Client: Must be able to handle prompt.

Server: Enforce restrictions on table entries.

PromptedSubscriberslimits the number of entries in the prompted subscribers table. When user A subscribes to user B’s presence, user B receives a prompt indicating that user A is now subscribed to user B’s presence. After user B accepts or acknowledges this prompt, the corresponding entry in the PromptedSubscriberstable is deleted. If user B does not respond to these prompts, the table can fill up leaving no room for subscription prompts from other users. This does not cause problems if user B ignores all subscription prompts. For most Office Communicator users the number of subscription prompts will be small. A nonhuman presentity, such as a bot or other application, might be designed to ignore subscription prompts, thereby avoiding the use of the PromptedSubscriberstable altogether. This can be achieved by setting PromptedSubscribersto 0, meaning that subscription prompts to the presentity are not needed.