ZyXEL Communications P-27xx Series User Manual page 19

Note: Enter any advanced SIP configuration information as it was given to you by
your SIP service provider. If you do not have any advanced configuration
information, you can skip this section.
Figure 5 Advanced SIP Settings (part 1)
The following table describes the labels in this screen.
Table 2 SIP Setting
LABEL
SIP Port
Media Port
Packetization
P-27XX Series User's Guide
DESCRIPTION
Enter the port number on your ZyXEL Device that SIP calls made with
the selected phone should use.
Enter the port number on your ZyXEL Device that RTP media packets
should use.
Select the voice codec packetization interval in milliseconds. The default
is 20 ms. This is used to minimize loss that happens during
transmission of voice data over the network.
The packetization interval effectivately sets the size of each voice
sample contained within a data packet. At 20 ms, the codec employed
in digitizing the voice signal can usually compensate for data
degredation and attenuation by using Packet Loss Concealment (PLC).
However, if the loss becomes too great, noticeable distortion occurs.
Setting the packetization interval higher, however, may introduce more
problems depending on the codec (such as G.711). Other codecs (such
as G.729 and G.723) have improved PLC techniques and as such can
also withstand a higher packetization interval; this means more packets
can be lost in transit without a noticeable loss in quality.
Chapter 3 Phone Use and Configuration
19