Operation Manual

AT-RG213 Residential VoIP Gateway - SIP Software Reference Manual
SIP Software Release 6-0-0
J613-M0524-00
72
Port Impedance
The FXS port impedance must match the phone one to guarantee the
maximum quality and avoid annoying echo. The Table 22 shows the
equivalent circuits that can be configured for the FXS ports and their
corresponding name.
Table 22. FXS Port equivalent circuits
Tone Name Description
600r
600 Ω
600c
600 Ω
2.2 µF
900c
900 Ω
2.2 µF
cplx1
820 Ω
100 nF
220 Ω
cplx2
50 nF
100 Ω
800 Ω
Buffer Management
As show in Figure 21, the RTP packet coming from the network, before being
played back, goes in a circular buffer. The frames are passed from this buffer
to the DSP only when a number of frames are accumulated.
The dimensioning of these two parameters: length of the buffer and its
threshold can be configured and must be chosen to guarantee a tradeoff
between immunity to packet arrival time and introduced delay.