Which statement about SS& message routing and addressing methods is true?

Question

Options

• AThe SGSN does not know the subscriber IMSI
• BMessages can be addressed in two ways: by IMSI and by GTT
• CAll configuration areas are required, especially if the routing is based purely on DPC+SSN
• DThere are three ways to address an SS7 message: by IMSI, by GTT and by DPC + SSN

• A
  5% (3)
• B
  9% (5)
• C
  2% (1)
• D
  84% (48)

Explanation

Option D is correct because SS7 message routing supports exactly three addressing methods: IMSI (the subscriber's unique identity), GTT (Global Title Translation) (which translates a logical address like a phone number into network routing info), and DPC+SSN (Destination Point Code + Subsystem Number, which directly identifies the network node and application). Together, these cover the full spectrum from subscriber-level to network-level addressing.

Why the distractors are wrong:

• A is false - the SGSN absolutely knows the subscriber's IMSI; it uses it for authentication and mobility management.
• B is incomplete - it correctly names two methods but omits the third (DPC+SSN), making the statement false.
• C is backwards - when routing is based purely on DPC+SSN, GTT configuration is not required, because you're bypassing Global Title Translation entirely; GTT is only needed when you lack a direct point code.

Memory tip: Use the acronym "IGD" - IMSI (who the subscriber is), GTT (translate a logical address to a route), DPC+SSN (go directly to the destination node). Three layers: subscriber → logical → physical.

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