php toolkit retrieve a list of the possible values for a multiselect field

Hi,

I'm sure this will have been asked and answered before but I've searched the forum and can't find it.
  
  I'm using the php toolkit: "PHPToolkit_2015_1".
  
  I'm running a search that returns a list of customers that includes a custom field of the type multiselect (SearchColumnSelectCustomField). An example return for this custom field is: {"name":null,"internalId":27,"externalId":null,"typeId":423} where the internalId varies by customer.
  
  I need to get the name of this field for each customer.
  
  I guess there may be two ways:
  
  1) I assume there is a way to get all the possible values (select options) of this field using either the typeId or the custom field name. If so could someone please tell me how or point me to where I can find it.