JavaScript to pull an attribute from Owning user.

Hi,

So I'm looking to use JavaScript to pull information from a related record while not specifically on its page.

An example:

I am on an Opportunity page and the owner is "Jeff". I want to use javascript to get any custom attribute of the user Jeff, "e.g. phone number". Can I do this while on the opportunity page?

Kind of like the idea that I want to use:

Xrm.Page.getAttribute("phone_number").getValue();

but instead of the current "Page" I want to set it to the Jeff's page and grab his phone_number attribute (whose GUID I have). Not that of the Opportunity page. 

Is that possible?