Loopback Call Routing In CME

pitviper

I stumbled on this on the Cisco site - Interesting...

Loopback Call Routing
Loopback call routing in a Cisco Unified CME system is provided through a mechanism called
loopback-dn, which provides a software-based limited emulation of back-to-back physical voice ports
connected together to provide a loopback call-routing path for voice calls.
Loopback call routing and loopback-dn restricts the passage of call-transfer and call-forwarding
supplementary service requests through the loopback. Instead of passing these requests through, the
loopback-dn mechanism attempts to service the requests locally. This allows loopback-dn configurations
to be used in call paths where one of the external devices does not support call transfer or call forwarding.

Control messages that request call transfer or call forwarding are
intercepted at the loopback virtual port and serviced on the local voice gateway. If needed, this
mechanism creates VoIP-to-VoIP call-routing paths.

Loopback call routing may be used for routing H.323 calls to Cisco Unity Express. For information on
configuring Cisco Unity Express, see the Cisco Unity Express documentation.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmeloop.pdf

chmorin

Very interesting. I am still not entirely sure what it does. Does this allows us to allow a means for call transfer/hold when an external call does not support it? It looks like it does more than that too.

I'm still very much a nub to voice concepts.

pitviper

Looked like an interesting way to hairpin VOIP calls. It appears pretty limited though; no transcoding which means G.711 over the WAN.