[Home](./index.md) > [sip.js](./sip.js.md) > [Subscription](./sip.js.subscription.md) ## Subscription class A subscription provides [Notification](./sip.js.notification.md) of events. Signature: ```typescript export declare abstract class Subscription ``` ## Remarks See [Subscriber](./sip.js.subscriber.md) for details on establishing a subscription. The constructor for this class is marked as internal. Third-party code should not call the constructor directly or create subclasses that extend the `Subscription` class. ## Properties | Property | Modifiers | Type | Description | | --- | --- | --- | --- | | [data](./sip.js.subscription.data.md) | | any | Property reserved for use by instance owner. | | [delegate](./sip.js.subscription.delegate.md) | | SubscriptionDelegate | undefined | Subscription delegate. See [SubscriptionDelegate](./sip.js.subscriptiondelegate.md) for details. | | [dialog](./sip.js.subscription.dialog.md) | | SubscriptionDialog | undefined | The subscribed subscription dialog. | | [state](./sip.js.subscription.state.md) | | SubscriptionState | Subscription state. See [SubscriptionState](./sip.js.subscriptionstate.md) for details. | | [stateChange](./sip.js.subscription.statechange.md) | | Emitter<SubscriptionState> | Emits when the subscription state property changes. | ## Methods | Method | Modifiers | Description | | --- | --- | --- | | [dispose()](./sip.js.subscription.dispose.md) | | Destructor. | | [subscribe(options)](./sip.js.subscription.subscribe.md) | | Sends a re-SUBSCRIBE request if the subscription is "active". | | [unsubscribe(options)](./sip.js.subscription.unsubscribe.md) | | Unsubscribe from event notifications. |