14.12.1.1. Call Routing of external alphanumeric SIP URIs 
OpenScape 4000 must route video calls using an external SIP URI address to the
defined SBC (if more than one SBC is installed). External means the dialed SIP-URI
is not assigned to an OpenScape 4000 subscriber or is within the own or a trusted
domain.
OpenScape 4000 must forward/ route SIP URI calls without modifying the dialed
alphanumeric SIP-URI. This allows the next SIP peer to route the call to the correct
destination without the loss of important parameters (e.g. port)
OpenScape 4000 must route SIP URI Invites with an unknown domain to a predefined SBC
(e.g. SBC1), using wildcard routing.
Additionally OpenScape 4000 must route SIP URI Invites with specific domains to
predefined SBCs (domain based routing to the trunk towards SBC, e.g. domain
“customer1.com” should be routed to SBC2, domain “customer2.com” should be routed
to
SBC3).