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Note: One VoIP call uses two RTP ports: one for RTP and the other for RTCP. If GT48 has two FXS trunks and
each trunk supports 24 lines, then one GT48 can support up to 48 lines, which means the minimum number of
RTP ports required is 96. If RTP port number is less than 96, that means you cannot make 48 calls at the same
time. The default values are set from 10010 to 10030. You do not need to change them.
Step 7: In the First Digit Timeout field, enter the time (in second) allowed for the dialing of the first digit. When a
line goes off-hook, if within the time specified here the first digit has not been dialed, GT48 will treat this
as an abandoned called and will indicate to the caller to go on hook. The default value is 12.
Step 8: In the Inter Digit Timeout field, enter the time (in second) allowed for the dialing of the middle digits.
Counting from the last digit dialed, if within the time specified here no digit has been dialed, the system
will send the dialed string out. The default value is 12.
Step 9: In the Critical Dgt Timeout field, enter the time (in second) for finished dialing. This parameter is used in
conjunction with x.T in the Digit Map. After the specified head of the number in the rule has been dialed, if
within the time specified here no digit has been dialed, GT48 will send the dialed number out. The default
value is 5. For example, if there is 021.T in the Digit Map, after the caller dials 021, if within the specified
time (for example, 5 seconds) no digit has been dialed, 021 will be sent out.
Step 10: In the DTMF Mode field, use the down arrow to select the transmission mode. This parameter is used to
set DTMF signal transmission mode. Options are Audio, 2833, and INFO. Audio is transparent
transmission mode; INFO is information transmit mode; 2833 is RTP data packet transmit mode.
Step 11: In the Default codec field, enter the codec GT48 supports. GT48 supports G729A/20, G723/30,
PCMU/20, and PCMA/20. You can enter multiple values here, each value being separated by a comma.
When multiple encoding modes are entered, the gateway will process the communication by selecting
sequentially the encoding mode supported by both sides.
Codec supported by GT48
Codec mode
Time interval of RTP packets transmission(unit: ms)
G729A/20 G.729A
20
G723/30 G.723
30
PCMU/20 G.711
20
PCMA/20 G.711
20
Step 12: In the Echo cancellation field, select on to invoke echo cancellation and off to turn off echo
cancellation.
Step 13: Click the Submit button.
5.3 Network
Configuration
Step1. Click the Network Config link of the left side of Figure 5 – 1. The following displays: