Which of the following statements are CORRECT About PRA and QSIG trunks on U1900? (Multiple Choice)

Question

Options

• AThese two types of trunks are the same, and their configurations are the same.
• BA PRA trunk uses DSS1 signaling as the control signaling, while a QSIG trunk uses QSIG
• CThe signaling used by these two types of trunks is based on network/user model.
• DFor an El trunk, if one end is a PRA trunk and the other end is a QSIG trunk, the two devices at the

• A
  6% (2)
• B
  79% (27)
• D
  15% (5)

Explanation

B is correct because PRA (Primary Rate Access) and QSIG are distinct trunk types that use different Layer 3 signaling protocols: PRA uses DSS1 (Digital Subscriber Signaling System No. 1), which is a user-to-network protocol, while QSIG uses its own QSIG protocol designed for inter-PBX communication.

C is correct because both DSS1 (used by PRA) and QSIG are Q-series signaling protocols built on a network/user model - DSS1 operates in user mode on the subscriber side and network mode on the exchange side, and QSIG similarly defines symmetric master/slave roles based on this same conceptual model.

A is wrong because PRA and QSIG are fundamentally different trunk types with different signaling protocols and different configuration parameters - they cannot be used interchangeably.

D is wrong (or incomplete as stated) because connecting a PRA trunk on one end to a QSIG trunk on the other end of an E1 link creates a signaling mismatch - both sides must use the same protocol for the trunk to function correctly.

Memory tip: Think of the initials - PRA = DSS1 (P→D, both "plain" user-to-network protocols), and QSIG = QSIG (the name is its own protocol). Both sit on the "Q-series" foundation, which is why C holds - they share the network/user role model rooted in ITU-T Q-series specifications.

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