When messages exceed the maximum size of the SS7 packet 
(272 octets) the message must be segmented. This message 
type is used to send an additional segment to the 
destination signaling point.

A message, sent in either direction during the setup or 
active phase of the call(ex.inbetween ACM and ANM), 
indicating that an event, which is of significance, and 
should be relayed to the originating or terminating access, 
has occurred.

Consider any call fowarding scenario.... As soon as switch 
receives Setup, it checks that the Called_Party has 
forwarded option activated and so tries to forward the 
call. Meanwhile, Switch sends CPG message towards 
originator saying that Call is in Progress.

protocol testing is testing the performance and evaluate 
it in  working conditions

for wireless i have tried GlomoSim simulator, as it has
ability to test 100 nodes on single cpu and for thousands of
nodes multiprocessor and parallel version is reqd.

doegar

Protocol testing to find that protocol request /resposnse 
working properly your produt and to test performance 
that it

communication between two vendors(different product makers)is
done via the protocol messages based on international
standards.to check that we've to use the tools which
supports and generate the protocol messages.
I've used the tools..,
1)abacus 5000>>>>SIP,ISUP,H248
2)MGTS-ISUP protocol messages

Protocol testing is the testing the protocol's 
functionality. Any given protocol should function accordin 
to its RFC. Protcol testing involves testing functionality, 
protocol stack, interoperability, performance etc... 
I have tested SIP protocol using Ethereal tool. Ethereal is 
used to capture protocol packets and to analyze them. Some 
other tools we can use are Etherpeek, abacus 5000, Nethawk. 
Wireshark etc..

Protocol testing means to test the functionality of the
node(piece of software) which should compliance to some
standard message flow. For this one should take a
tester(Testing Unit) which should send standard messages to
the node(Item under test). Above all tester mentioned are
good but according to me K1297-G20(Tektronics)is the best
tester.
Advantages
1) Many standard Protocol are supported by this tester
2) One can add just new protocol supports easily
3) With introduction of G-20 its interface is really good,
one can easily learn.

Disadvantages
1) Load can't be tested with this, as this tester is windows
based with low processing capabilities
2) It is little bit costly as it give license per link per
protocol base
3) Support too have some issues
 
I think because of its high cost small companies don't use
it and also big shots doesn't have enough number K1297-G20

Protocol testing ensures proper functionality of various
elements of a message. It also ensures whether it has
designed as per specification.
   When we are talking about protocol testing then we must
be aware of two tools. i.e. Analyser and Simulator. Job of
analyser to ensures proper decoding along with Call and
session analysis. Job of simulator is to simulate various
entities of networking element.
e.g. In GSMA interface we may simulate BSC, where the system
under test may be MSC.
I ve used 
NetHawk EAST simulator 
Analyser: 
NetHawk M5,RADCOM, WIRESHARK etc.