Registration; Loss Plan; Echo Cancellation; Clock Synchronization - Nortel 1110 Fundamentals

222 Nortel IP Softphone 2050

Registration

When you add an IP Softphone 2050 to the network, depending on
configuration, the IP Softphone 2050 can connect to a predefined IP address
or can request an IP address from a DHCP server. The IP Softphone 2050
then contacts the Connect Server, which instructs the IP Softphone 2050
to display a message on its display screen requesting the customer node
number and TN.
After the customer enters this information, the IP Softphone 2050 contacts
the Node Master, which selects a TPS with sufficient capacity to register the
IP Softphone 2050. The IP Softphone 2050 contacts the chosen TPS and, if
the IP Softphone 2050 is valid, registers it with the system. The registration
information is then saved to the IP Softphone 2050.

Loss plan

The USB Headset Adapter provides the IP Softphone 2050 with a fixed loss
plan compliant with the TIA-810A specification. If other headsets or audio
devices are used, the loss plan is unknown and undefined. Nortel supports
the resolution of audio problems only for the USB Headset Adapter.

Echo cancellation

Echo can be generated electrically when an impedance mismatch occurs,
or generated acoustically by feedback from a speaker or ear piece to a
microphone. Any echo that is ultimately returned to the IP Phone is more
noticeable to the listener because of the additional delay introduced by
the IP connection.
The Voice Gateway Media Card has echo cancelers included as part of
its function that cancels echo generated on the TDM side of the Media
Gateway. When audio goes through the Voice Gateway Media Card, the
echo cancellers are enabled.
The IP Softphone 2050 has no echo canceller, so a slight echo from
acoustic coupling on the headset can occur in some call situations.

Clock synchronization

Buffer underruns and overruns can occur since no sample clock is at the
receiving end of an IP audio stream synchronized to the transmitting clock.
The buffer overruns and underruns are corrected by two mechanisms,
both of which apply to the IP Phones and the DSPs on the Voice Gateway
Media Card.

Jitter buffer

Use the default value sent from the TPS (the value configured in TM–
[Nortel recommends that you use the default value]) to configure the IP
Softphone 2050 jitter buffer.
Copyright © 2003–2007, Nortel Networks
.
Nortel Communication Server 1000
IP Phones Fundamentals
NN43001-368 01.02 Standard
Release 5.0 20 June 2007