[cisco-voip] IP overhead paging: likes and dislikes? SIP andsurvivability...

[Robert Kulagowski]

Lelio Fulgenzi wrote:
> Not sure if this helps or not, but I have found that a router is always 
> in SRST mode, well, ready to accept registrations anyways. As long as 
> dial-peers are programmed to gateways, etc, then things will work. So, 
> this means, if a phone can't talk to the CUCM, but the SRST router can, 
> you will have phones registering, but not able to dial off-net because 
> the router's gateways are still registered to the CUCM, not the router.

I've been thinking, and maybe that's dangerous, but I could be overthinking 
this?

Can this be deployed as essentially a hoot-and-holler?

I thought I could configure a dial-peer like so:

dial-peer voice 10 voip
session protocol multicast
destination-pattern 123456
session target ipv4:239.1.2.3:20000
codec g711ulaw


Put the speakers into a multicast group called 239.1.2.3 and then whenever 
someone dials x123456 they'd start talking into the multicast group.

But then I saw this thread:
http://puck.nether.net/pipermail/cisco-voip/2009-May/001302.html

Which makes me think that you actually need two T1's on the same router, 
cross-connected in order to dial-in to a multicast session?  That would 
seem totally wasteful...

So here's what I'm trying to figure out.

1) If I have speakers that are SIP endpoints, then I can't configure them 
for auto-answer, because I can't do auto-answer on more than one DN, so I 
can't do a page group.
2) If I have speakers that are set for multicast, then I can set them up 
like this:
http://www.cyberdata.net/support/server/documentation/Setting_Up_MGROUPS_in_Cisco_Call_Manager_Express.pdf
But that doesn't help me when the site _isn't_ in CME mode?
3) I thought of using something like a TCL script running on a router, 
where it accepts a VOIP call leg then broadcasts it over multicast.  But 
the TCL built-in to the routers doesn't have udp send capability?
4)  Just buy a bunch of special-purpose boxes.  But then I need one for sip 
to multicast and another for "ipod audio" to multicast...