Joao, go to system ---- phonebook --- options ---- check that the option MATCH EXACTLY is enabled and apply the settings.
Then in the CRM integration, click on the TEST button and enter the number of an existing contact in the CRM, the result should be the contact details. With that you can test that the system is doing the contact lookup in the CRM.
Now, please note that the caller id sent from the voip provider must MATCH the caller id of the contact, otherwise you will need to reformat it.
Call journaling will exist when the contact exist in the CRM, and if does not exist, then the agent can create it as new one.