We use MC Email Studio (synced with the connector to Sales Cloud) to contact Subscribers via email and use the Salesforce PersonContactId as the Contact Key for all our sends.
We are implementing Mobile Push and have noticed MC created separate Contact records using the Device ID as the Contact Key, how can we avoid this and correctly associate devices to existing Contacts?
You should understand that Mobile Push handles both Unknown and Identified mobile contacts.
First, start from your Use cases and decide if you want to target only Identified contacts or more widely also Unknown contacts (called also devices / app holders / mobile prospects).
After installing your mobile application and before logging into it, a contact is still unknown. You will have to choose if you want to have him in your MobilePush contact list.
If yes, intilializing the SDK will create a new mobile push contact with a random GUID generated automatically.
If no, you will have to delay Registration Until a Contact Key is set.
When this contact logs in your application, you will have to retrieve the PersonContactId and register it using the SDK.
If you choosed to have Unknown contacts, they will be converted into an identified contact after registration ( the GUID will be updated by PersonContactId for the same Device ID)
In order to retrieve the PersonContactID, I believe that you already have it as part of your authentication Service. If not, you will have to implement an API Call to the Salesforce Platform prior to registering the contact in MobilePush SDK.
You handle contactkey registration within the SDK
iOS - 'Registration Updates Via Contact Key, Attributes, and Tags'
Android - 'Registration Updates Via Contact Key, Attributes, and Tags'
You can configure the SDK in a mode that delays registration until a contact key is set by the application. Use this configuration mode only in implementations where the device running your app is tied to a specific contact key in Marketing Cloud and not to a generic device contact.
