SSCA VoIP Architecture 2

Question 1

In a VoIP network, what is the primary role of a Session Border Controller (SBC)?

Accepted Answer

To control and secure SIP sessions at network borders

Answer

An SBC sits at the boundary between networks to enforce security policies, NAT traversal, and session control for SIP traffic.

Question 2

Which VoIP architecture component is responsible for translating E.164 telephone numbers to SIP URIs?

Accepted Answer

ENUM server

Answer

ENUM (E.164 Number Mapping) uses DNS to map telephone numbers to SIP URIs and other internet resources.

Question 3

What distinguishes a Softswitch Class 4 from a Class 5 in VoIP architecture?

Accepted Answer

Class 4 handles transit/carrier routing; Class 5 handles end-user features

Answer

Class 4 softswitches handle inter-carrier routing and transit traffic, while Class 5 softswitches provide retail features to end users.

Question 4

In VoIP, what is the purpose of STUN (Session Traversal Utilities for NAT)?

Accepted Answer

To help endpoints discover their public IP address and port behind a NAT

Answer

STUN allows a VoIP client behind a NAT to discover its external IP address and port mapping for media connectivity.

Question 5

Which protocol is used to carry the actual voice media (audio) in most VoIP deployments?

Accepted Answer

RTP

Answer

RTP (Real-time Transport Protocol) carries the encoded audio and video media streams in VoIP calls.

(SSCA) Sip School Certified Associate Practice Test