DBL Technology GoIP User Manual page 27

The table below summaries all the parameters defined in this section.
Parameter
(Advanced VoIP)
1. SIP Listening Port Mode
 Port Number
2. SIP INVIITE Response
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Description
SIP Local port defines the network port number that the device listens for incoming SIP
messages. This port number is sent to the SIP Sever/Proxy during SIP registration.
This setting defines if this port is pre-assigned to a fixed number or a randomly
generated port number (5060 to 6060).
This specifies the port number when the SIP Local Port Mode is set to "Fixed".
One of the key function of the device is to allow call terminations from VoIP to GSM.
In general, a VoIP caller dials a PSTN or GSM number (E.164) number and the SIP Server
routes this call to the device by sending a SIP INVITE message. This parameter
specifies the response to the INVITE message. The three possible responses are
described in details below.
1. SIP 200 OK - This response inform the SIP server that the call is answered and the
call duration timers starts immediately. If billing applies, the call is charged
(immediately) even before the call is answered.
2. SIP 180 then 183 - The device first sends back a SIP 180 Ringing to the calling SIP
device to generate a local ring. The caller hears a ringback tone immediately
after the call is dialed. When a ringback tone is received from the GSM network,
a SIP 183 Session In Progress message is sent to the calling party to start early
media (before the call is answered). This allows to the caller to hear the ringback
from the GSM network. This is done in order to avoid a long silent period before
a ringback tone is returned from the GSM network.
3. SIP 183 - The device sends back a SIP 183 Session In Progress message to the
calling SIP device. The calling SIP device then goes into early media mode to
GoIP User Manual
Default Value
5060
SIP 180 then
183
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