[Asterisk-Users] pseudo load balancing?

[Damon Estep]

In an environment with multiple asterisk boxes, each with a 4PRI card
and 4PRIs (92 Zap ports) and oversubscription on SIP peers, is there a
way to get the asterisk box to use the Zap interfaces on another box in
times of congestion? While the oversubscription ration would be
optimized for the number of Zap ports, there is always the possibility
of an "unusual" load.

What about if a single DID number for a single user were configured to
come in on any of the PRIs connected to any of the * boxes, and it ended
up coming in to a different box than the SIP peer is configured for, can
* route the call?

Is 4PRIs too much for a single box (3ghz single or dual cpu) assuming
all calls are either Zap<--->SIP SIP<---->Zap, no low bit rate codecs
are used (g.711 only), and every SIP peer also has a voicemail box? 

Can this be done? Are there any consultants hanging out here that have
real world experience with this?

Damon