1-9
Cisco VG248 Analog Phone Gateway Software Configuration Guide
OL-1209-02
Chapter 1 Overview
Supported Analog Devices
Speakerphones
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.
Private Line Automatic Ringdown Phones
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.
Fax Machines
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
for details).
Modems
The VG248 supports modems in pass-through mode.
