Subject: Consideration of Interworking

From: "Welton, Jonathan" <[email-masked]>
Date: Mon, 8 Nov 1999 14:38:52 -0000

To all Spirits

I am interested in the requirements imposed on Spirits by the needs of
interconnect, that is the interworking between companies, possibly
competitors, in order to deliver services. Allowing interconnect on these
services is generally desirable, and in certain countries it may be a
regulatory requirement.

This will require certain Spirits interfaces to be 'hardened' for
interconnect. In the Spirits Physical Architecture, figure 1 of draft00, I
assume this will primarily impact interfaces E and A, the Spirits Server to
SCP/SN interfaces, although interface B (Spirits Server to SMS) may also be
affected.
Another approach, more in line with PINT I believe, would be to have an
InterWorking Function (IWF) or firewall through which all communication
between the Spirits Server and the Network Operator would be filtered.

Interface B raises some interesting problems. For example, for Internet Call
Waiting there may be a need to instruct the local switch to deactivate
normal voice call waiting, and forward on busy to the the internet service
provider (Spirits Server presumably). At the end of the call the reverse
action would be needed.  But Network Operators would be very wary of
allowing other organisations to control customers' line features on local
switches. This is in addition to the difficulty of invoking what is usually
a management action in a real-time scenario.

Best of luck with your Washington meeting. I hope you can find some time to
consider the needs of interconnect.

Jonathan Welton