Importing and updating contacts
with 
To automate the import and update of contacts from one application to another.
Emails, SMS and voice messages
with
To automate the sending of messages between Digitaleo and your application.
What you can do
Synchronise your contacts on one side only
For example: create a contact in Digitaleo when the latter is created in Salesforce.
Automate your SMS, emails and voice messages
For example : send an email to a prospect using Digitaleo when the prospect is created in Salesforce.