Contacts and Devices

The contact key, also known as a subscriber key, is a unique identifier for a contact in MobilePush. Use this value to associate cross-channel addresses and subscriptions for a single contact. You can use the same key for a contact across multiple channels, such as email, SMS, and push messaging.

Use a unique value for the contact key. Examples of unique values include universally unique identifiers (UUIDs), an email address, or a mobile phone number. If you don’t specify a contact key, MobilePush generates a UUID when the SDK is initialized. In cases where anonymous users aren’t relevant, wait to initialize the SDK until your desired contact key is determined.

You can update a record’s contact key at any time. For example, you can associate a user with the same key you use to identify email subscribers.

In Marketing Cloud Engagement, a device ID is a unique identifier for one mobile device. A contact can have multiple mobile devices, but a device can’t have multiple contacts. If a new contact logs in to a device, Marketing Cloud Engagement associates the device with the new contact key. It takes about 15 minutes for the device to be associated with the new contact key.