Hello, we have a phone system add-on which looks up matching NS customers based on their phone numbers.  This works fine from a .NET C# application with the following code:

            // Create and setup the phoneNumber search string
            SearchStringField phoneNumber = new SearchStringField();
            phoneNumber.@operator = SearchStringFieldOperator.contains;
            phoneNumber.operatorSpecified = true;
            phoneNumber.searchValue = strNumber;

            CustomerSearchBasic custSearchBasic = new CustomerSearchBasic();
            custSearchBasic.phone = phoneNumber;

            CustomerSearch custSearch = new CustomerSearch();
            custSearch.basic = custSearchBasic;

            SearchResult response = m_NSService.search(custSearch);

We then added two custom Entity phone number fields to our Customers.  I can search for matches on one of the fields like so:

            SearchStringCustomField customField6 = new SearchStringCustomField();
            customField6.