The Contact Import API is designed for bulk importing/updating of contacts.
A POST to the API is identical to /api/v1/contact. However, the Import API does not return the DSID of newly created contact. Rather the create operation is queued, allowing for this API to be much faster than the Create or Edit a Contact API.
Body of POST
The body of the POST must include a JSON representation of the Contact. The only field that is required is an email address or mobile phone number.