S
COOPY
+ S - User Manual
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8.2.
Overview of the SIP protocol
8.2.1.
What is SIP?
SIP is for Session Initiation Protocol, a protocol specified by the IETF for establishing media transmission
sessions. SIP is considered the communication protocol of the future by most vendors, and as such it has
deep influence on the VoIP applications.
As a signalling protocol, SIP brings methods and techniques to solve the issues related to the
establishing of an audio link. Almost as important, it is a recognised standard, implemented on many
network devices and systems. Using SIP helps you build modular and really evolutive systems, not being
tied to a single vendor.
The SIP protocol is an essential requirement in the EBU Tech 3326 recommendation (a.k.a. "N/ACIP"
recommendation, from the name of the EBU workgroup who elaborated it).
8.2.2.
Setting a link with SIP
Let us look at an example (diagram below): a reporter on the move with a S
COOPY
+
1
wants to make a call
to a SIP compliant codec located in the main station. The reporter may be at home, or at another
location, not necessarily known in advance.
Once the S
COOPY
+ is on and connected to the network, it will register itself
to a SIP "registrar". This
registrar can be located on the LAN of the radio house, but it may as well be elsewhere in the network.
Then the registrar "knows" where the S
COOPY
+ is, what its IP address is. On the radio house side, a
similar process takes place
.
To call the codec of the radio house (e.g. a Scoop 5), the reporter just needs to know its SIP address,
which can be like
(indeed very similar to an e-mail address). To call the
unit, the reporter has to select the preferred audio coding mode on the S
COOPY
+ (e.g. mono G722), then
call the remote unit, simply using this SIP address (SIP URI).
Figure 11 – Setting up an SIP session with server(s)
1 is a portable audio codec from AETA; the description here applies to any other SIP compliant codec.
S IP
p r o x y s e r v e r
S I P
r e g i s t ra r
IP
n e tw o r k
S c o o p y +
IP te le p h o n e
G a te w a y
1
2
3
4
5
S c o o p 5
G a te w a y
G a te w a y
