As per your query on messages/dialogues interchange let me clarify to you that:::
MAP MESSAGES ARE THEMSELVES ROUTED ON THE BASIS OF GT.
I take a simple example using analogy:
If YOU are at DELHI and you want to send some LETTER to ME at BANGALORE.
Then you place that LETTER into an ENVELOP and put my ADDRESS over it.
This LETTER reaches POST OFFICE where address is analysed and finally the LETTER reaches me.
Now in the above example just replace the following words as:
YOU = SSN of MSC/VLR.
LETTER= MAP or CC Message/dialogue.
ME = SSN of HLR.
ENVELOPE= Sinalling PACKET.
ADDRESS= GLOBAL TITLE.
POST OFFICE= GT Translator.
I think I have made my point pretty clear..that MAP or CC messages are themselves piggy backed over packets which are routed on the basis Of GT.
PS: This page is too heavy for my dialup i-net connection.,so pls send any queries regarding this directly to email@example.com