declare	@t table (dt datetime)

insert	@t
select	'02-Jan-2007' union all
select	'01-Feb-2007' union all
select	'10-Feb-2007' union all
select	'28-Feb-2007' union all
select	'18-Mar-2007'

DECLARE	@DaysRange INT,
	@NumOfCalls INT

SELECT	@DaysRange = 35,
	@NumOfCalls = 4

SELECT		t1.dt AS theDate
FROM		@t AS t1
CROSS JOIN	@t AS t2
WHERE			t2.dt >= DATEADD(day, DATEDIFF(day, 0, t1.dt), 0)
			AND t2.dt < DATEADD(day, DATEDIFF(day, 0, t1.dt), @DaysRange)
		OR
			t2.dt >= DATEADD(day, DATEDIFF(day, @DaysRange, t1.dt), 1)
			AND t2.dt < DATEADD(day, DATEDIFF(day, 0, t1.dt), 1)
GROUP BY	t1.dt
HAVING		COUNT(*) >= @NumOfCalls

-- Prepare sample data
set dateformat mdy

declare @process table (caseid int, processid int, procstartdate datetime, procenddate datetime)

insert	@process
select	10, 1, '02-28-2005', '06-17-2005' union all
select	10, 2, '06-18-2005', '07-21-2005' union all 
select	10, 3, '07-22-2005', '10-11-2005' union all
select	20, 1, '03-21-2005', '07-24-2005' union all
select	20, 2, '07-25-2005', '08-10-2005'

declare @letters table (caseid int, letterlogid int, entrydate datetime, amtofletters int)

insert	@letters
select	10, 101, '04-15-2005', 1 union all
select	10, 102, '07-20-2005', 1 union all
select	10, 103, '09-16-2005', 1 union all
select	20, 201, '06-14-2005', 1 union all
select	20, 202, '06-19-2005', 1 union all
select	20, 203, '07-27-2005', 1 union all
select	20, 204, '07-29-2005', 1

declare	@phonecalls table (caseid int, phonelogid int, entrydate datetime, amtofphonecalls int)

insert	@phonecalls
select	10, 4101, '04-17-2005', 1 union all
select	10, 4102, '07-24-2005', 1 union all
select	10, 4103, '09-18-2005', 1 union all
select	10, 4104, '09-23-2005', 1 union all
select	10, 4105, '09-25-2005', 1 union all
select	20, 4106, '06-18-2005', 1 union all
select	20, 4107, '06-20-2005', 1 union all
select	20, 4108, '07-28-2005', 1 union all
select	20, 4109, '07-29-2005', 1 

-- First try, INNER JOINs on LEFT JOINs GROUP BYs
SELECT		x.CaseID,
		x.ProcessID,
		ISNULL(x.AmtOfLetters, 0) AS AmtOfLetters,
		ISNULL(y.AmtOfPhoneCalls, 0) AS AmtOfPhoneCalls
FROM		(
			SELECT		p.CaseID,
					p.ProcessID,
					SUM(l.AmtOfLetters) AS AmtOfLetters
			FROM		@Process AS p
			LEFT JOIN	@Letters AS l ON l.CaseID = p.CaseID AND l.EntryDate BETWEEN p.ProcStartDate AND p.ProcEndDate
			GROUP BY	p.CaseID,
					p.ProcessID
		) AS x
INNER JOIN	(
			SELECT		p.CaseID,
					p.ProcessID,
					SUM(c.AmtOfPhoneCalls) AS AmtOfPhoneCalls
			FROM		@Process AS p
			LEFT JOIN	@PhoneCalls AS c ON c.CaseID = p.CaseID AND c.EntryDate BETWEEN p.ProcStartDate AND p.ProcEndDate
			GROUP BY	p.CaseID,
					p.ProcessID
		) AS y ON y.CaseID = x.CaseID AND y.ProcessID = x.ProcessID
ORDER BY	x.CaseID,
		x.ProcessID

-- Second try, INNER JOINs on UNIONs
SELECT		CaseID,
		ProcessID,
		SUM(AmtOfLetters) AS AmtOfLetters,
		SUM(AmfOfPhoneCalls) AS AmfOfPhoneCalls
FROM		(
			SELECT		p.CaseID,
					p.ProcessID,
					l.AmtOfLetters,
					0 AS AmfOfPhoneCalls
			FROM		@Process AS p
			INNER JOIN	@Letters AS l ON l.CaseID = p.CaseID AND l.EntryDate BETWEEN p.ProcStartDate AND p.ProcEndDate

			UNION ALL

			SELECT		p.CaseID,
					p.ProcessID,
					0,
					c.AmtOfPhoneCalls
			FROM		@Process AS p
			INNER JOIN	@PhoneCalls AS c ON c.CaseID = p.CaseID AND c.EntryDate BETWEEN p.ProcStartDate AND p.ProcEndDate

			UNION ALL

			SELECT		p.CaseID,
					p.ProcessID,
					0,
					0
			FROM		@Process AS p
		) AS x
GROUP BY	CaseID,
		ProcessID
ORDER BY	CaseID,
		ProcessID

-- Third try, LEFT JOINs on UNIONs
SELECT		CaseID,
		ProcessID,
		SUM(AmtOfLetters) AS AmtOfLetters,
		SUM(AmfOfPhoneCalls) AS AmfOfPhoneCalls
FROM		(
			SELECT		p.CaseID,
					p.ProcessID,
					ISNULL(l.AmtOfLetters, 0) AS AmtOfLetters,
					0 AS AmfOfPhoneCalls
			FROM		@Process AS p
			LEFT JOIN	@Letters AS l ON l.CaseID = p.CaseID AND l.EntryDate BETWEEN p.ProcStartDate AND p.ProcEndDate

			UNION ALL

			SELECT		p.CaseID,
					p.ProcessID,
					0,
					ISNULL(c.AmtOfPhoneCalls, 0)
			FROM		@Process AS p
			LEFT JOIN	@PhoneCalls AS c ON c.CaseID = p.CaseID AND c.EntryDate BETWEEN p.ProcStartDate AND p.ProcEndDate
		) AS x
GROUP BY	CaseID,
		ProcessID
ORDER BY	CaseID,
		ProcessID