This is a typical application for "Grouping", which is explained, with
examples,
in http://www.w3.org/TR/xslt20/#grouping.

Except for the HTML tags, this should do it:

  <xsl:template match="/caller">
    <xsl:for-each-group select="contact" group-by="@callID">
      Call connected on <xsl:value-of select="@timeCallInitiated"/>.
      There are <xsl:value-of select="count(current-group())"/>
related connections as follows:
      <xsl:for-each select="current-group()">
        Connection: <xsl:value-of select="@timeAgentConnected"/> to
agent <xsl:value-of select="@agent"/>
      </xsl:for-each>
    </xsl:for-each-group>
  </xsl:template>

-W
PS: Seems like you got an answer, so you do know how to ask ;-)

On Fri, Feb 5, 2010 at 11:46 PM, Robert Bourdeau <rhbourdeau@xxxxxxxxx>
wrote:
>
> Consider the following XML document, showing a set of telephone calls
> received from a specific telephone number, along with the various
> internal connections to different employees from the time the call is
> first connected to the phone system until the call is terminated.
>
>
> <caller callerID="9195551212">
>    <contact
>        callID="1"
>        contactID="3"
>        timeCallInitiated="2010-02-04T09:42:58"
>        timeAgentConnected="2010-02-04T09:43:23"
>        agent="Jamie Smith"
>    />
>    <contact
>        callID="1"
>        contactID="2"
>        timeCallInitiated="2010-02-04T09:42:58"
>        timeAgentConnected="2010-02-04T09:43:23"
>        agent="Angela Jones"
>    />
>    <contact
>        callID="1"
>        contactID="1"
>        timeCallInitiated="2010-02-04T09:42:58"
>        timeAgentConnected="2010-02-04T09:42:58"
>        agent="Desi Johnson"
>    />
>    <contact
>        callID="2"
>        contactID="3"
>        timeCallInitiated="2010-02-04T09:41:45"
>        timeAgentConnected="2010-02-04T09:42:10"
>        agent="Jamie Smith"
>    />
>    <contact
>        callID="2"
>        contactID="2"
>        timeCallInitiated="2010-02-04T09:41:45"
>        timeAgentConnected="2010-02-04T09:42:10"
>        agent="Angela Jones"
>    />
>    <contact
>        callID="2"
>        contactID="1"
>        timeCallInitiated="2010-02-04T09:41:45"
>        timeAgentConnected="2010-02-04T09:41:45"
>        agent="Julia Billings"
>    />
>    <contact
>        callID="3"
>        contactID="2"
>        timeCallInitiated="2010-01-26T13:29:21"
>        timeAgentConnected="2010-01-26T13:29:49"
>        agent="Angela Jones"
>    />
>    <contact
>        callID="3"
>        contactID="1"
>        timeCallInitiated="2010-01-26T13:29:21"
>        timeAgentConnected="2010-01-26T13:29:21"
>        agent="Desi Johnson"
>    />
> </caller>
>
> Ideally this XML file would be one level deeper where all "contacts"
> having the same value for the callID attribute are grouped together
> under a single node. I cannot change that however. And therein lies my
> problem. To dumb this down I'd like output as follows:
>
>        Call Connected on 2010-02-04
>        There are 3 related connections as follows:
>        Connection: 2010-02-04T09:43:23 to agent Jamie Smith
>        Connection: 2010-02-04T09:43:23 to agent Angela Jones
>        Connection: 2010-02-04T09:42:58 to agent Desi Johnson
>        Call Connected on 2010-02-04
>        There are 3 related connections as follows:
>        Connection: 2010-02-04T09:42:10 to agent Jamie Smith
>        Connection: 2010-02-04T09:42:10 to agent Angela Jones
>        Connection: 2010-02-04T09:41:45 to agent Julia Billings
>        Call Connected on 2010-01-26
>        There are 2 related connections as follows:
>        Connection: 2010-01-26T13:29:49 to agent Angela Jones
>        Connection: 2010-01-26T13:29:21 to agent Desi Johnson
>
> The Key problem is just one little piece of this:
>        'There are 3 related connections as follows:'
> How do I get the '3' computed?
>
> For my application, it is important that I output that number BEFORE I
> output each of the connections.
> Here's the code to produce that output above (with one incomplete part):
>
>        <xsl:template match="/caller">
>          <xsl:for-each select="contact">
>            <xsl:if test="not(@callID =
preceding-sibling::contact[1]/@callID)">
>                <br/>
>                Call connected on <xsl:value-of
> select="scripts:justDate(@timeCallInitiated)"/>
>                <br/>
>                There are
>                <xsl:value-of select="count(/caller/contact[@callID = ?])"/>
>                related connections as follows:
>            </xsl:if>
>
>            <br/>
>            Connection:
>                <xsl:value-of select="@timeAgentConnected"/>
>            to agent
>                <xsl:value-of select="@agent"/>
>          </xsl:for-each>
>        </xsl:template>
>
> See that question mark '?' up there? What goes there? The @callID
> refers to the context of the preceding XPath expression. I want to
> only count those 'contact' nodes that have the same attribute value of
> 'callID' as the node being currently processed by the for-each node.
> But I have no idea how to reference the context of the for-each node
> from within that count function.
>
> I clearly need a better theoretical understanding of how different
> contexts are used in the XSL processing. But there seems to be a large
> gap between the technical documentation at w3c and how to even ASK
> about problems like this!
>
> Any help here?
>
> A totally alternative approach to the XSL stylesheet is perfectly
acceptable.
>
> Best
>
> Robert H. Bourdeau