RADVision L2W-323 User Manual page 36

Overview
request an "outside line" from the Gateway, all you have to dial is a configurable service
prefix before the destination phone number.
A service prefix is an identifier string composed of up to 31 characters. Valid characters are
0 through 9 and pound (#), asterisk (*) or comma (,). For example, 90* would be identified
by the Gateway as a service prefix. The system administrator that defines service prefixes is
responsible for informing the network users of the available Gateway services.
Each service you define can be assigned to one or more of the Gateway WAN ports. You
can also make a service exclusive to a particular port by assigning it only to that port. When
a service is assigned to several ports, and the Gateway receives a call request for this
service, the Gateway searches for the first available WAN port supporting the requested
service. This is known as Line Hunting.
The Gatekeeper also provides services, and the services you define for the Gateway have to
be defined with the Gatekeeper. For more information, see "Making Calls," page 2-18.
Processing a Service Request
When the Gateway receives a service request from an endpoint on the LAN, it identifies the
service prefix at the beginning of the dialed string, and routes the call through the
appropriate WAN port. The L2W-323 Gateway tries to connect the call to the destination
terminal or phone.
Incoming Call Routing Methods
WAN terminals or phones access the Gateway via phone numbers. The Gateway WAN port
is directly or indirectly connected to an ISDN line that is assigned at least one phone
number by the Telephone Company.
BRI ISDN lines usually have one phone number per B channel and in Europe, MSN
(Multiple Subscriber Numbering) is common. In MSN, one BRI line is assigned more than
one number per channel.
When a terminal or phone on the WAN wants to reach a LAN endpoint, it has to dial at least
one of the phone numbers assigned to the Gateway WAN ports.
The WAN terminal determines the type of connection—voice or video.
When a call originating on the WAN reaches the L2W-323 Gateway, the Gateway has to
forward it to a LAN endpoint. This is achieved through one of the several incoming call
routing methods the Gateway supports.
The Gateway supports four incoming call routing methods in the following order of priority:
multiple subscriber numbering (MSN), TCS4 (for H.320 calls), interactive voice response
(IVR) and default extension. You can assign one or more of these methods to each of the
WAN ports.
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