Re: MWI handling

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Gregg -

Just to summarise that very long last post....in case it comes over
as a 'do it this way' type of view - it shouldn't

There is no requirement to use sub addressing but if there is some
division that an application naturally fits around then it makes it far
more presentable and also brings the addressing of the individual
enpoints outside of the block content which aids subsequent parsing and
context.. In the CTI schema there is as yet no definition of how this
sub addressing should be implemented, originally it was centric around a
telephone 'line' approach but as we've found this does not scale or
adapt well for say VOIP.

In my xAPTel implementation I have used this line approach but
adapted it within the VOIP/Skype section by using  a 'call' segmentation
such that the entire duration of such a call from commencement to
cessation is on one UID but the UID's are re-used from a pool. For
VOIP/Skype I additionally use a service 'line' advertisment that itself
goes out on a  specific UID (but perhaps should arguably be an
application announcement) which is effectively a line that is always
free. This marks the base UID of all calls placed using that service. I
am not saying this is correct, or ideal but it works and that is how xAP
Switchboard picks up the concurrent calls, if you want Asterisk to work
with xAP Switchboard 'out of the box' then this is the approach used.
Bear in mind we focussed these applications at SOHO installations. I
used service announcemenat capabilities such that we could determine how
to cross route a call eg placing an ordinary PSTN call back over VOIP
using the ident vPSTN.

If however there is a better use of sub addressing , and I am sure
there is,  that fits more naturally against a VOIP model (and if it does
that it will probably be retrofittable against less complex models) then
I think we should adopt that for the CTI schema. I'm very much open to a
suggestion here .   It may well be that there is no alternative but to
drop down to a much smaller use of sub addressing, perhaps where
"VOIP"
is one sub address as one style of interface and Skype is another and
PSTN another and then the blocks contain more contextual data and the
same sub address is used concurrently for many calls differentiated by
the call 'tag' . Alternatively by implementing a much longer UID you
could even use the tag as the UID - there are an unlimited number of
UID's effectively in the new scheme and hence a UID would be unique to
that call (but may realistically rollover after some number of calls).
It may also be that sub addressing is not approriate in that although
there are many possible candidates for such a division none fit
naturally.  Such a schema might best be developed as initially an
Asterisk schema and then renamed and dropped into a new CTI schema or
I'm happy to encompass it within the CTI schema from the start as long
as we consider CTI as all devices and not just Asterisk.

There is no 'right and wrong' currently with xAP - as long as the
messages conform to the protocol , there are many ways to create a
solution - finding the right one takes a lot of experimentation,
particularly for somethings as complex as CTI .... All I offered was how
we'd implemented it with xAPTel / xAPSwitchboard - one take on the
subject   I'd very much welcome a better way as I do recognise that
'calls' or 'lines' in not perhaps ideal sub addressing..

Kevin