3Com NBX, Руководство по установке

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Configuring IP Telephony 189
Low-bandwidth
Telephony
To support remote users, you can configure a 3Com Telephone to operate
over a low-bandwidth link. For reliable audio, the link must support
throughput of at least 64 Kbps. An example is a single B channel of a
Basic Rate Interface (BRI) ISDN line or a single channel on a T1 line.
An ISDN connection is not the only method of connecting a remote
telephone. The ability of NBX systems to operate in Ethernet (Layer 2)
mode or IP (Layer 3) mode gives you several connection options such as
cable modem, frame relay, and DSL. Your 3Com NBX Voice-Authorized
Partner can help you to design a system to meet your needs.
You enable low-bandwidth communications in an NBX system at the
device level using the NBX NetSet utility.
To enable low-bandwidth communication for a telephone:
1 Log in to the NBX NetSet utility using the administrator name and
password.
2 Click Telephone Configuration > Telephones .
3 Select the telephone from the list by clicking its extension.
4 When the Modify page opens, enable these check boxes:
■
Disable Line Appearance/BLF
■
Disable Conferencing
■
Disable Paging Output
■
Disable Periodic Status Message
Disabling these features reduces the network traffic, but the
low-bandwidth telephone cannot play music on hold, initiate a page or
participate in conference calls.
5 In the Audio Compression Settings, make sure Lowest Bandwidth
Utilization is selected.
The rest of the configuration is done at the telephone and at the router.
At the telephone, you specify the IP address of the NCP. See
“Manually
Configuring Telephone IP Settings” on page 185 . When your
low-bandwidth link is operational and connected to the NCP, the Auto
Discover process can discover and configure the telephone, or you can
manually configure it through the NBX NetSet utility.
You can operate with the link “always open” or you can set it up to
autodial. With an autodial connection, when you lift the receiver on the
telephone, the ISDN router or terminal adapter establishes the link to the