Hi, 

>>Consider a PSTN call.  The call goes from the gateway to softswitch / 
>>Proxy.  Proxy routes to VM App Server.  INFO has to pass through 
>>softswitch / Proxy. 
>>In KPML-land, VM App Server *directly* subscribes to UAC key press
state, bypassing the softswitch.

[Christer] As I've said before, there are environments where some
proxies must (for whatever reason) be passed through. I guess an
outbound proxy is a good example.

>>KPML and INFO have the same number of messages for a SINGLE digit;
KPML wins 
>>hands-down for multiple digits or reports.
> 
>Not exactly - for a single digit, KPML would generate a 
>Subscribe/200/Notify/200 before the single DTMF was even 
>pressed - before the actual Notify with the digits in it.  
>And of course there is now also a subscribe dialog involved.  
>Assuming a one-shot single digit type, then, we're talking 6 
>SIP messages for KPML vs. 2 for Info.  

[Christer] And, in cases where you need to send DTMFs (or whatever
information) in both directions you actually need 2 subscription dialogs
- one in each direction, and maintaining dialog state also consumes
resources. And, in some cases you may not even know whether you will
ever have to use the dialog.


>>More importantly, let's take a Call Management (CM) application that 
>>calls a VM application when they cannot find the subscriber.  INFO has

>>to pass through the softswitch / Proxy to the CM application.  Cool - 
>>it is a proxy, so it knows to relay.  But OOPS!  The CM application 
>>has to proxy the INFOs to the VM application.  Yes - you could be a 
>>good programmer and remember to do that EVERYWHERE you place an 
>>outbound call, but it is really easy to get wrong.
> 
>I'm not sure I understand the scenario.  The VM learned about 
>this call how?
>By being in the signaling path, no?  So why wouldn't the CM 
>forward INFO along the path? (I mean it is in the same 
>dialog, after all)  Now I don't doubt it could screw that up, 
>and eat the info thinking it was for itself, but lots of 
>things can get screwed up - my guess is KPML will not be 
>impervious to screw ups.

[Christer] I also have problems understanding the scenario. INFO is
routed to wherever the INVITE that initiated the dialog was routed...

Regards,

Christer


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