3com SuperStack 3 NBX Manual De Usuario

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The H.323 Connection
401
POTS Adapters
You can purchase circuit boards that plug into a personal computer and 
adapt an analog telephone (POTS) for use with an H.323 connection.
H.323 Gatekeepers
The gatekeeper is an H.323 entity on the network that provides address 
translation and controls access to the network for H.323 terminals, 
Gateways, and MCUs. The gatekeeper also provides services to the 
terminals, Gateways, and MCUs, such as managing bandwidth and 
locating Gateways.
The H.323 
Connection
H.323 calls between local and remote NBX Business and Basic Telephones 
are transparent to users, except for the IP dial plan. The Call Processor 
sets up the local end of the H.323 call as though it were setting up a call 
through a line card. However, this connection actually goes to a network 
interface card (NIC) in a dedicated Windows 2000 or Windows NT system 
that is running the ConneXtions software.
The Call Processor requests an H.323 port in the ConneXtions software 
by sending a frame, with a simulated Ethernet address, that contains a 
requested IP address. The ConneXtions gateway uses this address to 
request a level three connection between the local router and the remote 
router associated with another PBX or NBX system. 
After an IP connection has been established, the ConneXtions software 
begins a series of H.323 exchanges by using TCP packets on the IP 
connection.
These H.323 exchanges set up the call and negotiate the type of voice 
compression that is used. They also cause the remote NBX (or PBX) 
system to begin setting up the remote end of the connection.