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© Virtual Access 2016
GW6600 Series and GW6600V Series User Manual
Issue: 1.5
Page 144 of 384
15
ISDN pseudowire
ISDN pseudowire is an optional interface on the GW6600 and GW7600 Series.
15.1
Introduction
ISDN pseudowire is delivered via an ISDN S/T interface in NT mode. This allows you to
connect existing ISDN equipment with BRI interfaces, such as phones, audio contribution
boxes, and so on, directly to the Virtual Access router.
When the ISDN equipment attempts to make a call, its messages are converted into
SIP/RTP protocol and relayed to a provider, such as the GW7610-PRI. The GW7610-PRI
is connected directly to a real ISDN network and converts the messages received over
SIP/RTP back into native ISDN messages for the real ISDN network.
In this way, access to the real ISDN network is extended to the remote site over IP and
the equipment at the remote site that is connected to GW6610-ISDN will be able to
make and receive calls to and from any number on the real network.
The router is equipped with an ADSL WAN interface and is the interface of choice for
connecting the device to the core network.
Note: success of the pseudowire relies on the network’s ability to transfer the data
without loss between the Virtual Access router and the provider. IP packet loss will result
in momentary corruption of data, typically around 20 milliseconds in length. If you apply
a codec to the data content, the codec may need to resynchronise the data stream,
resulting in a larger outage of length determined solely by the codec.
When configuring ISDN pseudowire, you must decide the device’s role. A device typically
acts as a client, which is the usual role for a GW6610-ISDN provider or for GW6610-
ISDN in a back-to-back scenario.
The following sections explain the configuration of two scenarios using a GW6610-ISDN
as an example.
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GW6610-ISDN in client role
o
This allows ISDN user equipment connected to the GW6610-ISDN unit to
reach, or be reached from any number on the ISDN network available at
the provider, typically a GW7610-PRI.
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GW6610-ISDN in client and provider role
o
This allows ISDN user equipment connected to the GW6610-ISDN unit on
one site connect to ISDN user equipment at another site, where there is
another GW6610-ISDN unit.