One way of doing this is to create TWO records for every call record.
One record to contain START date/time and an indicator set to "S", and
the second to contain END date/time and an indicator set to "E". So,
in E2 you can have a formula:

=B2+C2

for the START records (with "S" in F2), and for the END records you
can have this in E2:

=B2+C2+D2

and "E" in F2. I'm assuming you have just copied the sheet of call
records to the same workbook, so one sheet will be START records and
the other sheet will be END records.

Merge the two sets of records together and sort by date/time (column
E) in ascending sequence. With the S/E indicator in column F, and
assuming first record is in row 2, then in G2 add the formula:

=IF(F2="S",G1+1,G1-1)

and copy this down to all other records (cell G1 should be initialised
to 0 or left blank). Column G should then contain number of
simultaneous calls at any one time. You can easily determine the
maximum number (using the MAX function) AND the number of times that
this number, and every lower number, was reached (using the COUNTIF
function).

As you still have the date and time in separate columns, it is
relatively easy to obtain summary tables by date and time.

Hope this helps.

Pete

On Jul 11, 4:42*pm, Ber wrote:
On a spreadsheet of calls as example below made from different extension
numbers, what I am trying to determine is how many ext Nos ( Maximum) *are on
a call *together i.e. at the same time say between 9 and 10 o clock then 10
and 11 then 11 and 12 etc etc on any particular date can anyone help please
we are trying to work out peak usage hours. This is a huge spreadsheet over
months with all calls made recorded and we just want to know our peak usgae
hours over the months. Hope I've made this clear and thanks in advance.
Ext NO *Date (dd/MM/yyyy) * * * Time * *Duration
3224 * *01/11/2007 * * *08:47 * 0:00:28
3336 * *01/11/2007 * * *09:25 * 0:00:34
3219 * *01/11/2007 * * *09:51 * 0:00:33
3278 * *01/11/2007 * * *10:07 * 0:00:25
3016 * *01/11/2007 * * *10:19 * 0:00:50
3161 * *01/11/2007 * * *10:32 * 0:00:00
3161 * *01/11/2007 * * *10:37 * 0:00:00
3311 * *01/11/2007 * * *11:48 * 0:00:03
3318 * *01/11/2007 * * *11:54 * 0:00:04
3133 * *01/11/2007 * * *12:11 * 0:00:37
3318 * *01/11/2007 * * *12:22 * 0:00:21
3133 * *01/11/2007 * * *12:23 * 0:00:00
3133 * *01/11/2007 * * *12:27 * 0:00:04
3133 * *01/11/2007 * * *12:29 * 0:01:59
3133 * *01/11/2007 * * *14:25 * 0:00:53
3380 * *01/11/2007 * * *14:58 * 0:00:16
3333 * *01/11/2007 * * *15:10 * 0:03:05
3380 * *01/11/2007 * * *15:12 * 0:00:26
3133 * *01/11/2007 * * *16:28 * 0:03:42
3133 * *01/11/2007 * * *17:02 * 0:03:59
3311 * *02/11/2007 * * *09:24 * 0:00:05
3311 * *02/11/2007 * * *09:33 * 0:00:05
3380 * *02/11/2007 * * *10:26 * 0:00:48
3299 * *02/11/2007 * * *11:17 * 0:01:22
3314 * *02/11/2007 * * *11:22 * 0:00:30
3016 * *02/11/2007 * * *11:55 * 0:00:14
3133 * *02/11/2007 * * *12:01 * 0:03:46
3278 * *02/11/2007 * * *12:16 * 0:01:06
3258 * *02/11/2007 * * *12:19 * 0:00:22
3133 * *02/11/2007 * * *12:37 * 0:00:21
3294 * *02/11/2007 * * *14:25 * 0:00:04
3294 * *02/11/2007 * * *14:25 * 0:00:00
3294 * *02/11/2007 * * *14:26 * 0:01:25
3294 * *02/11/2007 * * *14:28 * 0:01:40
3294 * *02/11/2007 * * *14:40 * 0:01:11
3152 * *02/11/2007 * * *14:57 * 0:02:45
3380 * *02/11/2007 * * *14:57 * 0:00:14
3318 * *02/11/2007 * * *16:45 * 0:00:20
3133 * *05/11/2007 * * *09:21 * 0:00:03
3133 * *05/11/2007 * * *09:22 * 0:00:05
3133 * *05/11/2007 * * *09:22 * 0:00:00
3133 * *05/11/2007 * * *09:27 * 0:01:15
3209 * *05/11/2007 * * *09:29 * 0:00:14
3133 * *05/11/2007 * * *09:30 * 0:02:43
3138 * *05/11/2007 * * *09:34 * 0:00:15
3133 * *05/11/2007 * * *09:43 * 0:00:23
3191 * *05/11/2007 * * *11:19 * 0:00:00
3205 * *05/11/2007 * * *11:21 * 0:01:21
3149 * *05/11/2007 * * *11:23 * 0:00:27
3278 * *05/11/2007 * * *11:41 * 0:00:20
3224 * *05/11/2007 * * *11:55 * 0:01:05
3224 * *05/11/2007 * * *12:00 * 0:00:02
3224 * *05/11/2007 * * *12:00 * 0:00:00
3224 * *05/11/2007 * * *12:04 * 0:01:37
3336 * *05/11/2007 * * *12:07 * 0:01:20
3133 * *05/11/2007 * * *12:14 * 0:01:28
3133 * *05/11/2007 * * *12:20 * 0:06:15
3133 * *05/11/2007 * * *12:29 * 0:00:19
3016 * *05/11/2007 * * *12:38 * 0:07:01
3133 * *05/11/2007 * * *12:39 * 0:02:43
3133 * *05/11/2007 * * *12:41 * 0:00:14
3352 * *05/11/2007 * * *14:23 * 0:01:22
3016 * *05/11/2007 * * *14:30 * 0:00:59
3336 * *05/11/2007 * * *16:25 * 0:01:23
3278 * *05/11/2007 * * *16:31 * 0:03:45
3152 * *06/11/2007 * * *11:25 * 0:00:40
3333 * *06/11/2007 * * *11:34 * 0:00:13
3032 * *06/11/2007 * * *11:40 * 0:00:44
3133 * *06/11/2007 * * *12:08 * 0:00:58
3133 * *06/11/2007 * * *12:09 * 0:00:20
3133 * *06/11/2007 * * *14:16 * 0:00:35
3278 * *06/11/2007 * * *14:45 * 0:00:13
3133 * *06/11/2007 * * *14:46 * 0:04:01
3016 * *06/11/2007 * * *15:26 * 0:00:14
3016 * *06/11/2007 * * *15:48 * 0:00:05
3016 * *06/11/2007 * * *16:13 * 0:00:09
3133 * *06/11/2007 * * *16:43 * 0:00:20
3133 * *06/11/2007 * * *16:45 * 0:00:37
3016 * *06/11/2007 * * *16:46 * 0:00:21
3224 * *07/11/2007 * * *08:56 * 0:00:55
3016 * *07/11/2007 * * *09:04 * 0:00:15
3016 * *07/11/2007 * * *09:17 * 0:01:07
3133 * *07/11/2007 * * *09:30 * 0:00:14
3278 * *07/11/2007 * * *09:38 * 0:01:05
3178 * *07/11/2007 * * *09:50 * 0:00:35
3259 * *07/11/2007 * * *09:58 * 0:00:39
3133 * *07/11/2007 * * *10:27 * 0:02:34
3191 * *07/11/2007 * * *10:40 * 0:00:00
3278 * *07/11/2007 * * *10:59 * 0:00:17
3470 * *07/11/2007 * * *11:16 * 0:00:00
3470 * *07/11/2007 * * *11:17 * 0:00:35
3044 * *07/11/2007 * * *12:23 * 0:01:00
3152 * *07/11/2007 * * *12:27 * 0:08:07
3336 * *07/11/2007 * * *12:31 * 0:01:28
3133 * *07/11/2007 * * *12:32 * 0:13:01
3039 * *07/11/2007 * * *12:43 * 0:00:51
3278 * *07/11/2007 * * *12:55 * 0:01:09
3045 * *07/11/2007 * * *13:01 * 0:00:16
3433 * *07/11/2007 * * *14:09 * 0:01:32
3433 * *07/11/2007 * * *14:12 * 0:02:36
3433 * *07/11/2007 * * *14:13 * 0:00:10
3230 * *07/11/2007 * * *14:28 * 0:02:09
3044 * *07/11/2007 * * *14:38 * 0:00:26
3158 * *07/11/2007 * * *14:44 * 0:01:05
3133 * *07/11/2007 * * *14:53 * 0:04:36
3044 * *07/11/2007 * * *15:16 * 0:00:04
3243 * *07/11/2007 * * *15:20 * 0:00:42
3133 * *07/11/2007 * * *15:22 * 0:00:24
3133 * *07/11/2007 * * *15:22 * 0:00:04
3278 * *07/11/2007 * * *15:25 * 0:00:00
3262 * *07/11/2007 * * *15:40 * 0:00:18
3044 * *07/11/2007 * * *15:53 * 0:00:04
3044 * *07/11/2007 * * *15:53 * 0:00:04
3278 * *07/11/2007 * * *16:03 * 0:00:19
3278 * *07/11/2007 * * *16:08 * 0:01:04
3016 * *07/11/2007 * * *16:12 * 0:00:12
3268 * *07/11/2007 * * *16:19 * 0:02:13
3380 * *07/11/2007 * * *16:28 * 0:02:39