Is it possible to create new unique leads/records without capturing an email address?

[Anonymous]

We're looking at leveraging the Marketo platform to capture customer information entered by an agent/sales rep, and then report out on this data. The agent won't have the customers emai, but will have their phone as a unique indetifier. 

Is it possible to set up a webform that creates new unique leads/records in the Markeo database from that phone number, instead of an email address? 

Thanks, 

[Anonymous]

You could just append the email address in a hidden field using some type of articial value or combination of firstlast and a default value. Then just allow that record to be ovewritten in the future.