CTA Customer Premises Equipment & Unified Communications 1 — Questions and Answers
Question 1: What is a PBX (Private Branch Exchange) and what function does it serve in enterprise telephony?
- A public telephone exchange owned by a carrier serving a city
- A private telephone switching system within an organization that connects internal extensions and provides shared access to external PSTN lines (Correct answer)
- A VoIP gateway connecting enterprise LANs to the internet
- A call recording system for compliance purposes
Correct answer: A private telephone switching system within an organization that connects internal extensions and provides shared access to external PSTN lines
A PBX manages internal extensions, voicemail, call routing, and shared PSTN trunk access within an enterprise, enabling employees to call each other via short extensions and share a smaller number of outside lines.
Question 2: What is the difference between an IP PBX and a hosted/cloud PBX?
- An IP PBX uses digital phones; a cloud PBX uses only analog phones
- An IP PBX is on-premises equipment owned and managed by the enterprise; a hosted/cloud PBX is operated by the provider off-site with service delivered via the internet (Correct answer)
- An IP PBX supports VoIP; a cloud PBX only supports PSTN calls
- IP PBX and cloud PBX are the same thing marketed differently
Correct answer: An IP PBX is on-premises equipment owned and managed by the enterprise; a hosted/cloud PBX is operated by the provider off-site with service delivered via the internet
IP PBX is CAPEX—enterprise-owned hardware on-site; hosted/cloud PBX is OPEX—the provider manages all the infrastructure and the enterprise subscribes as a service.
Question 3: What is UCaaS (Unified Communications as a Service)?
- An FCC program for universal broadband access
- A cloud-delivered model combining voice, video conferencing, messaging, and collaboration tools into a single integrated platform delivered as a subscription service (Correct answer)
- A hardware appliance that integrates PBX and Wi-Fi access points
- A security framework for enterprise communications
Correct answer: A cloud-delivered model combining voice, video conferencing, messaging, and collaboration tools into a single integrated platform delivered as a subscription service
UCaaS platforms like Microsoft Teams Phone, RingCentral, or Cisco Webex bundle voice, video, chat, and collaboration into a single cloud service, replacing multiple disparate communication systems.
Question 4: What is the function of a Session Border Controller (SBC) at an enterprise network boundary?
- To connect analog PBX systems to digital ISDN lines
- To secure and control VoIP traffic at the edge of a network, providing NAT traversal, protocol normalization, security, and call admission control for SIP trunks (Correct answer)
- To convert between IPv4 and IPv6 addressing for VoIP devices
- To record all VoIP calls for compliance archiving
Correct answer: To secure and control VoIP traffic at the edge of a network, providing NAT traversal, protocol normalization, security, and call admission control for SIP trunks
An SBC acts as a security and interoperability gateway for SIP trunks, protecting the enterprise from VoIP attacks, normalizing different SIP implementations, and handling NAT traversal.
Question 5: What is Power over Ethernet (PoE) and how does it benefit IP telephone deployments?
- A wireless standard for connecting phones to the network without cables
- A standard (IEEE 802.3af/at/bt) that delivers DC electrical power over Ethernet data cables, allowing IP phones and APs to operate without separate power supplies (Correct answer)
- A fiber optic power delivery system for remote equipment
- An electrical safety standard for data center UPS systems
Correct answer: A standard (IEEE 802.3af/at/bt) that delivers DC electrical power over Ethernet data cables, allowing IP phones and APs to operate without separate power supplies
PoE eliminates the need for separate power outlets at each IP phone location, simplifying installation and allowing phones to be powered from centralized UPS-protected PoE switches.
Question 6: What is the purpose of a 'hunt group' (or ring group) in a PBX or phone system?
- To route calls to the least recently used agent in a contact center queue
- To ring multiple phones (in sequence or simultaneously) when a single number is dialed, distributing incoming call load among a group of users (Correct answer)
- To track call history for billing purposes
- To provide voicemail for multiple users under a single mailbox
Correct answer: To ring multiple phones (in sequence or simultaneously) when a single number is dialed, distributing incoming call load among a group of users
Hunt groups distribute incoming calls across multiple phones/agents by hunting through them in sequence (linear) or ringing all simultaneously (blast), improving call answer rates.
CTA Customer Premises Equipment & Unified Communications 1
What is a PBX (Private Branch Exchange) and what function does it serve in enterprise telephony?