SS7

Next day I have to face an interview (actually two) in huawei technologies. So I am studying for it. Yesterday I have studied about SS7. this is Control channel signaling system no 7.
The standard defines the procedures and protocol by which network elements in the public switched telephone network (PSTN) exchange information over a digital signaling network to effect wireless (cellular) and wireline call setup, routing and control. This signaling is used to control the calls between PCN (personal communication network) and PSTN (public service telecommunication network). it includes some nodes like ssp(service switching point), scp(service control point) and signal transfer point. the ss7 protocol layers contains 3 MTP (message transfer protocol), SCCP (signaling connection control protocol), TCAP (transaction capabilities application part), ISUP (integrated services digital network user part), OMAP (operations, maintenance and administration part) and MAP (mobile application part).
MTP level-1: same as physical layer of OSI
MTP level-2: same as data link layer of OSI
MTP level-3 + SCCP: same as network layer of OSI, SCCP dose global title translation
ISUP: presentation+session+transport layer of OSI, also part of application and network layer
tacap+omap+map: application layer of OSI


I hope this info will help my other friends who will also face the interview today and tomorrow.