Add an item to a multivalue

Hi there...

I am attempting to extend a contact value. Creating a new contact as follows works fine :

var phone = {"main" : ['1234']};
e.person.phone = phone;

however when there is already data in the multivalue, I am unsure how to either construct a new one or append to the existing (such as adding an "iPhone" value). Constructing a new one would be troublesome as there may be any number of existing items to duplicate.

Regards,