One document matched: draft-rosen-ecrit-premature-disconnect-rqmts-02.xml

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [
<!ENTITY draft-ietf-ecrit-phonebcp SYSTEM "http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-ecrit-phonebcp.xml">
]>
<?rfc toc="yes" ?>
<?rfc symrefs="yes" ?>
<?rfc sortrefs="yes"?>
<?rfc iprnotified="no" ?>
<?rfc strict="yes" ?>
<?rfc compact='yes'?>
<rfc category="std" ipr="trust200811" docName="draft-rosen-ecrit-premature-disconnect-rqmts-02">
<front>
    <title abbrev="Abandoned Call/PrematureDisconnect">
       Requirements for handling abandoned calls and premature disconnects in emergency calls on the Internet
    </title>
    <author fullname="Brian Rosen" initials="B.R" surname="Rosen">
      <organization>NeuStar</organization>

      <address>
        <postal>
          <street>470 Conrad Dr.</street>
          <city>Mars</city>
          <region>PA</region>
          <code>16046</code>
          <country>US</country>
        </postal>
        <phone>+1 724 382 1051</phone>
        <email>br@brianrosen.net</email>
      </address>
    </author>
    <date month="January" day="5" year="2009" />
    <area>RAI</area>
    <workgroup>ecrit</workgroup>
    <keyword>I-D</keyword>
    <keyword>Internet-Draft</keyword>
    <keyword>geopriv</keyword>
    <keyword>location</keyword>
    <abstract>
      <t>
The -phonebcp draft currently requires endpoints to disable sending a BYE on an emergency call.  Insufficient justification
and lack of attention to the entire problem has caused comment on that section of the document.  This document attempts to define the
problem and the requirements to controlling disconnect on emergency calls.
      </t>
    </abstract>
</front>
<middle>
 
<section title="Problem Statement">
<t><xref target="I-D.ietf-ecrit-phonebcp"/> currently disallows sending of BYE by the calling UA.  This requirement has generated a request for
additional capability, and has also caused some to question why it is needed, and how the mechanisms interact with current and future 
emergency call systems.  There are two aspects of handing emergency calls that give rise to the discussion.</t>
<section title="Premature disconnect">
<t>Occasionally, when on an emergency call, a caller hangs up the call before the call taker is finished acquiring enough 
information. Emergency calls are stressful, and mistakes are inevitablely made. A mechanism is needed to re-establish communication 
between the caller and the call taker when this happens. The PSTN has a feature available, "Called Party Hold" (CPH) which is used 
in some jurisdictions to meet this requirement. If the user hangs up When CPH is engaged, the call is not torn down, 
but instead is maintained despite the "on hook" condition. The call taker may also have a mechanism (called "Ringback" which is different 
than call-back) to ring the user's telephone. If the handset is picked up, since the call is still active and resources 
maintained, the caller and the call taker are readily reconnected. Called Party Hold is a feature that has long been 
available in wireline networks, but is not currently implemented in wireless networks.  Some jurisdictions are desirous 
of maintaining their current PSAP call disconnect control capability, while other jurisdictions would like to regain 
access to those capabilities. Still, in other jurisdictions, the function may not be needed or desired, even in jurisdictions
that want to have the feature, it may not be desirable in all circumstances.  For example, if the call is queued due to congestion, 
it is undesirable to hold up the call and user initiated disconnect should be permitted.</t> 
</section>
<section title="Abandoned Call">
<t>It is not uncommon for an emergency call to be cancelled before it reaches a call taker. Abandoned, in this context, 
means that the call is terminated before a call taker answers it.  While it can be that the user is fully aware that 
the call is being cancelled, and considers the cancellation the most appropriate solution, abandoned calls are problematic 
to PSAPs because they don't know why the call was abandoned. Unfortunately, what looks like an abandoned call 
can be a more serious circumstance such as a hostage situation. In some jurisdictions, the PSAP dispatches a police unit 
to all logged abandoned calls.  In such jurisdictions, dispatching resources could be avoided for true inadvertent calling 
if the call went through, and the call taker was able to assess the actual situation. Other jurisdictions do not have the 
resources and may not respond to abandoned calls at all. As with premature disconnect, application of the function depends on conditions.
For example, in a mass calling event, an Interactive Media Response unit may be used to answer calls.
Abandoning a call answered by a machine may be appropriate. Even if jurisdictions respond to abandoned calls by 
dispatching emergency personnel in normal situations, they may not in this situation.</t>
<t>There is always a period of time after a call is initiated by a caller before there is any reasonable possibility to determine that
a call is abandoned.  Since the appication of special handling for abandoned call is dependent on conditions, there is an implication
that some form of negotiating is needed between the UAS and the UAC to invoke any kind of abandoned call processing.  This in turn
implies that if the call is abandoned before the signaling negotiation completes, no special handling should be provided. Accordingly,
an abandoned call is defined as a call which is attempted to be disconnected prior to the UAS answering, but after any signaling that 
would enable the feature is completed.</t>
<t>Retaining the connection is extremely important when there is no callback information (e.g., uninitialized phone) 
or the caller has call termination features active (such as call forwarding, do not disturb) and the PSAP is unable to reconnect via callback.</t> 
</section>
</section>
<section title="Requirements for Premature Disconnect">
<t>In the following discussion the entities are the humans who take part in the call.
<list style="hanging">
<t hangText="PD-1"> Some times, when a caller attempts to disconnect from an established emergency call, s/he may find that
disconnection appears not to work</t>
<t hangText="  Rationale:"> Some callers attempt to disconnect before the call taker has enough information to provide help.</t>
<t hangText="PD-2"> When a caller attempts to disconnect, the call taker gets an indication of such an attempt.  If the
device has a mechanical "hook switch" or similar mechanism that cannot be locked out, and the user picks up the handset, the call
taker gets an indication of that action.</t>
<t hangText="  Rationale:"> Knowledge of the caller action gives valuable information to the call 
taker which may influence how the call will be managed going forward.</t>
<t hangText="PD-4"> When PD-1 is enforced, the call taker must be able to cause alerting to the caller which 
has attempted to prematurely disconnect from the emergency call.</t>
<t hangText="  Rationale:"> The caller believes they have disconnected.  The ability to alert is needed to 
encourage the caller to reconnect.</t>
<t hangText="PD-5"> When PD-1 is enforced,the caller must not be able to place another call until the PSAP 
allows the call to be released.  This requirement is not intended to imply a user inteface with multiple lines accessible independently is locked to the single line
that placed the emergency call.  As mistakes can be made, an override mechanism invoked by the caller must be be feasible.  The implementation must fail safely such that the
phone cannot be locked and unable to call for help.</t>
<t hangText="  Rationale:"> Priority must be given to the call taker until such time she/he determines the call can be terminated.</t>
<t hangText="PD-6"> If the user responds to the alerting (PD-4), the caller and the call taker must be able to converse roughly immediately. "Roughly immediately" is 
in human terms: the time from when the caller reacts to
the alerting, initialting reconnect, and the time the call taker can resume conversing, and is perhaps a second.</t> 
<t hangText="  Rationale:"> If the user responds,  caller re-answers.</t>
<t hangText="PD-7"> Control of premature disconnect is not needed in all jurisdictions. It must be possible for the PSAP to not 
invoke the function and allow premature disconnect to terminate the call as if no special features were present.</t>
<t hangText="  Rationale:"> Whether the function is enabled is a call-by-call decision and takes into account the jurisdiction practice and conditions at the PSAP for the
call.</t>
</list></t>
</section>
    
<section title="Requirements for Abandoned Call">
<t>In the following discussion the entities are the humans who take part in the call.
<list style="hanging">
<t hangText="AC-1"> Where enabled, an emergency call, once "dialed" by the caller, completes even if the caller attempts to abandon it.  Normal mechanisms used by the
caller to disconnect appear to be disabled.</t>
<t hangText="  Rationale:"> Call takers cannot distinguish between calls which are appropriately abandoned and calls that 
need response but were cut short. Controls to limit abandonment are needed for those jurisdictions who would otherwise respond to all abandoned calls.</t> 
<t hangText="AC-2"> The user may note that in some circumstances, a disconnect request initiated very quickly after initiation does succeed.</t>
<t hangText="  Rationale:"> Disallowing call abandonment early minimizes the chances of abandoned calls, but since the conditions at the call taker have to be considered
before the mechanism can be invoked.</t>
<t hangText="AC-3"> The user may note that some times, the disconnect works.  This may depend on where s/he is calling from, or other conditions.  For example, disconnect
may work if the call is placed during a mass calling event.</t>
<t hangText="  Rationale:"> Whether the function is enabled is a call-by-call decision and takes into account the jurisdiction practice and conditions at the PSAP for the
call. .</t></list></t>  
</section>
    

<section title="IANA Considerations">
<t>There are no IANA Considerations for this document</t>
</section>

<section title="Security Considerations">
<t>If these features can be enabled by entities other than PSAPs, the entity may gain more control over the end device.  Failures of various
kinds may prohibit callers from being able to disconnect.</t>
</section>

<section title="Acknowledgments">
<t>
Thanks to Guy Caron, Theresa Reese, John Hearty, Ric Atkins, Anand Akundi and other members of the NENA i2.5 working group for their comments and suggestions on this draft.
</t>
</section>
  </middle>

  <back>
    <references title="Informative References">
      &draft-ietf-ecrit-phonebcp;
    </references>
  </back>
</rfc>