WITH q1 as (
SELECT * FROM
(VALUES
('q', 'a'),
('q', 's'),
('w', 'd'),
('w', 'f'),
('e', 'g'),
('e', 'h')
) q (col1, col2)
)
, q2
AS
(SELECT distinct col1 FROM q1)

SELECT
  q.col1,
  PhoneNumbers = COALESCE(STUFF
  (
    (
      SELECT ', ' + p.col2
        FROM q1 AS p
        WHERE p.col1 = q.col1
        ORDER BY p.col2
        FOR XML PATH('')
    ), 1, 2, N''
  ), N'')
FROM q2 q
ORDER BY q.col1;