Which of the following statements are CORRECT about R2 signaling? (Multiple Choice)

Question

Options

• AR2 signaling is a common channel signaling (CCS).
• BR2 signaling consists of line signaling and inter-register signaling.
• CRegister signaling in R2 signaling is inband signaling.
• DLine signaling in R2 signaling is used to transmit information such as numbers, user types, and

• A
  13% (3)
• B
  83% (20)
• D
  4% (1)

Explanation

B and C are correct because R2 signaling is structurally divided into two distinct components: line signaling (handling supervisory functions like seizure, answer, and release) and inter-register signaling (exchanging address digits and caller category). Register signaling transmits multi-frequency (MF) tones within the voice frequency band (300–3400 Hz), making it inband signaling by definition.

Why A is wrong: R2 is Channel Associated Signaling (CAS), not Common Channel Signaling (CCS). In R2/CAS, signaling is tied directly to each voice channel (e.g., using bit 16 in E1 frames for line signaling). CCS (like SS7) uses a dedicated separate channel for all signaling - a fundamentally different architecture.

Why D is wrong: The statement misattributes the role. Line signaling handles only supervisory/physical states (line idle, seizure, answer, clear). Transmitting numbers, user types, and categories is the job of register (inter-register) signaling, not line signaling.

Memory tip: Think "Registers Ring tones" - Register signaling uses audible MF tones (inband), while Line signaling uses silent frame bits (outband). And remember: R2 = CAS, not CCS - "R2 stays Close to its channel."

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