Here is a way to get these results without pivot, depending on indexes and data size it may be faster:
SELECT SystemID,
MAX('CallStarts') AS Statistic,
SUM(CASE WHEN Hour = 0 THEN CallStarts ELSE 0 END) AS Hr0,
SUM(CASE WHEN Hour = 1 THEN CallStarts ELSE 0 END) AS Hr1,
SUM(CASE WHEN Hour = 2 THEN CallStarts ELSE 0 END) AS Hr2,
SUM(CASE WHEN Hour = 3 THEN CallStarts ELSE 0 END) AS Hr3
FROM Table
GROUP BY SystemID
UNION ALL
SELECT SystemID,
MAX('AvgDuration') AS Statistic,
SUM(CASE WHEN Hour = 0 THEN AvgDuration ELSE 0 END) AS Hr0,
SUM(CASE WHEN Hour = 1 THEN AvgDuration ELSE 0 END) AS Hr1,
SUM(CASE WHEN Hour = 2 THEN AvgDuration ELSE 0 END) AS Hr2,
SUM(CASE WHEN Hour = 3 THEN AvgDuration ELSE 0 END) AS Hr3
FROM Table
GROUP BY SystemID
ORDER BY SystemID, Statistic ASC