
DBL Technology Co., Ltd.
GoIP User Manual
www.dbltek.com
Technical Support: [email protected]
63
To achieve the Call Back function, the SIP server calls the called party via its phone network and then
calls the SIP number. Since a call to this SIP number is set to forward to the phone number of the SMS
sender, both the called and calling parties can then be connected.
Example:
SMS content = 8675588228822
Sender’s number = 861380000000
SIP Server IP = 192.168.2.1
SIP Number = 20001
The INVITE message sent to the SIP Server is:
INVITE sip:[email protected]:5060;transport=udp SIP/2.0
Via: SIP/2.0/UDP 192.168.2.237:5060;branch=z9hG4bK363969813
From: <sip:[email protected]:5060>;user=phone;tag=65248630
To: <sip:[email protected]>
Call-ID: [email protected]
CSeq: 2 INVITE
Contact: <sip:[email protected]:5060>
Max-Forwards: 30
User-Agent: W
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, NOTIFY, REFER, REGISTER, MESSAGE, INFO, SUBSCRIBE
Content-Type: application/sdp
Content-Length: 226
c)
Mode 3
SIP Message format:
The “To” field in the SIP INVITE message contains the phone numbers of both the called and calling
parties. These two numbers are concatenated by using the asterisk (*) character with the number
of the called party in the front.
The “From” field contains the SIP number of the line that is associated with the GSM channel
Example:
SMS content = 8675588228822
Sender’s number = 861380000000
SIP Server IP = 192.168.2.1
SIP Number = 20001
The INVITE message sent to the SIP Server is:
Sending Message to 192.168.2.1:5060:
INVITE sip:8675588228822*[email protected]:5060;transport=udp SIP/2.0
Via: SIP/2.0/UDP 192.168.2.237:5060;branch=z9hG4bK363969813
From: <sip:[email protected]:5060>;user=phone;tag=65248630
To: <sip:8675588228822*[email protected]>
Call-ID: [email protected]
CSeq: 2 INVITE
Contact: <sip:[email protected]:5060>
Max-Forwards: 30
User-Agent:DBL
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, NOTIFY, REFER, REGISTER, MESSAGE, INFO, SUBSCRIBE
Content-Type: application/sdp
Content-Length: 226