Speakerphones; Private Line Automatic Ringdown Phones; Fax Machines; Modems - Cisco VG248 - Gateway Software Configuration Manual

Chapter 1 Overview

Speakerphones

Private Line Automatic Ringdown Phones

Fax Machines

Modems

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The VG248 performs line echo cancellation, but it does not perform acoustic echo
cancellation. Speakerphones with built-in echo cancellation such as the
Polycom-brand phones should work fine. However the voice quality might be
unsatisfactory when using a speakerphone that does not perform acoustic echo
cancellation itself.
A telephone configured as a Private Line Automatic Ringdown (PLAR) telephone
dials a pre-configured number when it goes off-hook. You cannot use PLAR
phones to dial any other numbers. Telephones in hotel lobbies and airports are
often configured in this way.
Cisco CallManager release 3.0 and later can be configured to support the PLAR
phone feature for an IP phone or for an analog telephone connected to the VG248.
The VG248 supports fax machines in pass-through and Cisco fax relay modes. In
fax pass-through mode, the gateways do not distinguish a fax call from a voice
call. Cisco fax relay offers a more reliable way of transporting the fax data in
order to increase the data rate. However, the terminating gateway must also
support Cisco fax relay. If necessary, you can disable Cisco fax relay (see the
"Disabling Cisco Fax Relay" section on page 3-3
The VG248 supports modems in pass-through mode.
Cisco VG248 Analog Phone Gateway Software Configuration Guide
Supported Analog Devices
for details).
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