Block Updates to a Field - Salesforce Sync

Hi Erica, 

You can specify what sources the field is blocking updates from (see below).  If you have a phone field in Marketo that is not synced to SFDC and a phone field in SFDC, the SFDC field will not write information to the Marketo phone number field when it is updated, unless you're running a data transformation campaign that is listening for a data value change.

Thank you Tara. So the source I am trying to use is the "Salesforce Sync."

I am trying to prevent the phone number that someone puts in a form from syncing to Salesforce.

Does this "Block updates from Salesforce Sync" work for this? I was thinking the "Salesforce sync" means syncing from Marketo to Salesforce and from Salesforce to Marketo.  Thank you!

Depends, do you care if it updates in Marketo?
 

If you don't, then just block field update on Sync, Import List, and Form Fill out

Yes, we want to see the new value in Marketo.

What we are trying to accomplish is to see the form data but for it not to automatically update in Saleforce. Our data in Salesforce is pretty clean (we are a relatively new company). Therefore, we want to prevent junk data from going into salesforce. However, if a valid phone number is submitted via the form - we want the option update that phone number in Saleforce manually.

One other thought I had was to make those fields - i.e. Phone number - "Read Only" for our Marketo-SFDC user. Would this accomplish what I am seeking?