Ady Wicaksono Daily Activities

I gave you an example of SS7 – GSM MAP log from my previous post about GSM – MAP. I will give you a picture of SS7 protocol stack and TCP/IP protocol stack so you could easily understand about SS7 if you understand TCP/IP or vice versa.

You see that GSM MAP – Mobile Application Part actually is similar with HTTP, SMTP and many other application layer on TCP/IP.

However, if on TCP/IP many application layer use user friendly protocol, not with SS7. For example, on SMTP Protocol, basically it’s very clear that Client (C) communicate with Server (S) like this:

C: EHLO localhost

S: 250 SMTP adywicaksono is ready

C: MAIL FROM: <testuser@domain.com>

S: 250 OK

……. and so on

But in GSM-MAP, you just talking about signalling means talking about bit & byte like this:

tc7e0 f15 d2d s00 i001b r0000 p(189)

4517090007320807001010151809040797440000000019199e400a915413131215000070206091553200a0050003e10201363c180c0693ddc2b78d0f447dbbf320213b9c9683d0e139681e4e9341e8f41c647ecbcbe9b31b047fb3d3e33c283d0789c66f375dfeb697e5f374982d0289eb74103a3d0785e170f93b3c4683de66503bcd4ed3c3f23c28eda697e5f6b29b9e7ebb41edfa9c0e1abfddf4b4bb5e7681926e5018d40eabdf72d01c5e2e8fd12c10ba0c9a87d31a000e010100

Yes, not user friendly for us but very effective & efficient for machine

Actually the meaning of this MAP protocol is like this:

MAP-MT-FORWARD-SHORT-MESSAGE-REQ

Parameter Key           :   23 (0x17) (Short message destination address (IMSI, LMSI, MS-ISDN roaming number or srv centre address))
Parameter Length        :    9 (0x9)
Parameter Value         : 000732080700101015
Parameter Key           :   24 (0x18) (Short message originating address (MS-ISDN or srv centre address))
Parameter Length        :    9 (0x9)
Parameter Value         : 040797440000000019
Parameter Key           :   25 (0x19) (Short message user data field)
Parameter Length        :  158 (0x9e)
Parameter Value         : 400a915413131215000070206091553200a0050003e10201363c180c0693ddc2b78d0f447dbbf320213b9c9683d0e139681e4e9341e8f41c647ecbcbe9b31b047fb3d3e33c283d0789c66f375dfeb697e5f374982d0289eb74103a3d0785e170f93b3c4683de66503bcd4ed3c3f23c28eda697e5f6b29b9e7ebb41edfa9c0e1abfddf4b4bb5e7681926e5018d40eabdf72d01c5e2e8fd12c10ba0c9a87d3
Parameter Key           :   26 (0x1a) (Srv centre has more short messages to send)
Parameter Key           :   14 (0xe) (invoke id)
Parameter Length       :    1 (0x1)
Parameter Value         : 0x01

Well, Short message user data field itself is also very complex.Read GSM 03.40, please )