Classic dilemma, but haven't found any clear best practice.
We have Email campaigns to encourage subscribers to Opt-in to SMS.
Something along - Text "JOIN" to XXXXX.
When someone texts JOIN, we see them in Mobile Connect, but the Contact Key is, as expected, the Mobile Number.
Assuming we already have the Mobile number on either Salesforce_Contact or on another DE, how do we bridge the data gap? (i.e. how can we use the Salesforce Contact ID (current SubscriberKey on Push and Email) - implemented also for SMS?
In other words what is the correct way to associate this Contact with an Existing contact ?
Thanks for your help!