Response to Call Back questions
IETF 77 – Anaheim
Stephen McCann, RIM
• Document contains some RIM responses to the 5
questions from Hannes Tschofenig, regarding Call
Call Back Q1
• What functionality is available in today's CS
• Disabling ‘a’ party clear is likely to be
implemented in some countries but we are unsure
of which countries.
Call Back Q2
• Is this useful functionality to have for IP-based
• The procedures in place for CS based emergency
services should be at least the same as for IP
based emergency services.
Call Back Q3
• Do you envision a time-restriction on this
• Example: only within one hour callbacks from the
PSAP are treated differently to normal calls.?
• The call back time needs to be configurable as it
is likely to be a national matter. In some countries
it may be zero.
Call Back Q4
• Would you expect the call to reach primarily the
device that initiated the emergency call?
• The call back should reach the device that made
the emergency call.
Call Back Q5
• In some cases the device that was used to originally initiate the call
does not respond anymore to a callback (e.g. imagine a fixed line
phone that was used to report a fire in a house and is out of order
soon afterwards). Since the initial emergency call provided a second
contact mechanism (namely the address of record) it could be used by
the call taker as well. Should this communication also experience the
same type of override privilege as the initially transmitted callback to
the emergency caller's device ?
• PSAP’s and emergency response services should be free to use
whatever means is appropriate and at their disposal to contact the
caller. It is beneficial for the caller’s device to provide more
information than the minimum required to the PSAP about location,
identify and alternative call back options.
Additional use case
• An emergency situation may change and the
caller awaiting a PSAP call back may desire that
the call back is made requiring the intervention of
the called user or without first alerting.
• Such a capability could be available for a limited
time. Imagine someone such as a kidnapped
person reporting that their life is in danger.