We want to undestand the proper way to use Get External Contact action. One of its inputs is the External Contact ID but we don´t know where should we start in order to get that exernal contact ID value, it is confusing!!!
Presumably you would know the id from doing a data dip, like using the Call Data Action.
If you don't know the id, use the Search External Contacts action instead. You can search using the phone number, email address or Twitter handle of the contact.