I think that this is brilliant!   I found this solution on SQL Authority’s site:

http://blog.sqlauthority.com/2009/11/25/sql-server-comma-separated-values-csv-from-table-column/

It is the most unique way of building a comma separated list in SQL that I have seen.    Most methods, and the ones I have used before as well, required building a user-defined function in SQL.  This one is unique in that it is:

1. Simple

2. can be used inline, in the SELECT statement.

Nice!   Thank you Pinal Dave!

For reference, his example code is :

SELECT SUBSTRING(
(SELECT ',' + s.ColumnName
FROM TableName s
ORDER BY s.ColumnName
FOR XML PATH('')),2,200000) AS CSV
GO

For me, I added it inline to a SELECT statement.

SELECT
 u1.UserId,
 u1.Department,
 u1.EmployeeID,
 u1.ReportsTo as [Manager Name],
 (
 SELECT SUBSTRING(
 (SELECT ',' + s.PhoneNumber
 FROM UserPhones s
 WHERE s.UserID=u1.UserId and PhoneStatus='Active'
 ORDER BY s.UserId, s.PhoneNumber
 FOR XML PATH('')),2,1000) AS CSV
 ) as ActivePhoneNumbers
 FROM Users as u1