CTA Customer Premises Equipment & Unified Communications 2 — Questions and Answers
Question 1: What is the E.164 numbering standard and where is it used?
- A fiber optic connector performance standard from TIA
- The ITU-T international telephone numbering plan defining the format of PSTN telephone numbers (country code + national number, up to 15 digits) (Correct answer)
- A DSL speed specification for residential broadband
- A data encryption standard for VoIP signaling
Correct answer: The ITU-T international telephone numbering plan defining the format of PSTN telephone numbers (country code + national number, up to 15 digits)
E.164 defines the global PSTN numbering format; a fully qualified E.164 number begins with '+' followed by the country code and national number, used for international call routing.
Question 2: In a contact center environment, what does 'ACD' stand for and what does it do?
- Automatic Call Distributor; routes incoming calls to the most appropriate available agent based on configured rules and skill groups (Correct answer)
- Analog Circuit Dialer; connects outbound calls over PSTN trunk lines
- Advanced Call Debug; a diagnostic tool for SIP troubleshooting
- Automated Content Delivery; streams hold music to callers
Correct answer: Automatic Call Distributor; routes incoming calls to the most appropriate available agent based on configured rules and skill groups
An ACD intelligently queues and distributes incoming calls to agents based on skills, availability, priority, or other business rules, forming the core of a contact center.
Question 3: What is the purpose of a 'codec' in VoIP telecommunications?
- To encrypt VoIP signaling messages between SIP endpoints
- To compress and decompress analog voice signals into digital data for IP transmission, trading off audio quality against bandwidth consumption (Correct answer)
- To convert between SIP and H.323 VoIP protocols
- To filter echo and background noise from voice streams
Correct answer: To compress and decompress analog voice signals into digital data for IP transmission, trading off audio quality against bandwidth consumption
VoIP codecs like G.711 (64 kbps, uncompressed), G.729 (8 kbps, compressed), and Opus trade audio quality for bandwidth efficiency, allowing voice to be packetized and transmitted over IP networks.
Question 4: What is 'Direct Inward Dialing' (DID) and why is it useful for enterprise phone systems?
- A type of PBX internal wiring that bypasses the operator
- A carrier service providing a block of telephone numbers that route calls directly to individual enterprise extensions without going through a receptionist or main number (Correct answer)
- An inbound call screening feature that blocks unrecognized numbers
- A regulatory requirement for 911 call routing in multi-tenant buildings
Correct answer: A carrier service providing a block of telephone numbers that route calls directly to individual enterprise extensions without going through a receptionist or main number
DID numbers allow external callers to dial directly to an employee's extension using a unique PSTN number, while the enterprise shares a smaller pool of actual PSTN trunk lines.
Question 5: What standard governs the provisioning of telephone numbers in the North American Numbering Plan (NANP)?
- ITU-T E.164 for international numbering only
- The NANP, administered by ATIS, using the NPA-NXX-XXXX format (area code - exchange - subscriber number) across the US, Canada, and 20+ countries (Correct answer)
- FCC Part 68 for CPE registration only
- ANSI T1.253 for SS7 signaling
Correct answer: The NANP, administered by ATIS, using the NPA-NXX-XXXX format (area code - exchange - subscriber number) across the US, Canada, and 20+ countries
The NANP defines 10-digit numbering (3-digit NPA area code + 3-digit NXX exchange + 4-digit subscriber number) and is administered by ATIS under FCC oversight.
Question 6: What is a 'softphone' in a unified communications environment?
- A physical phone with a touchscreen instead of buttons
- A software application on a PC, smartphone, or tablet that emulates a full-featured telephone, using VoIP to make and receive calls through the network (Correct answer)
- A low-cost analog telephone adapter
- A browser-based interface for voicemail management only
Correct answer: A software application on a PC, smartphone, or tablet that emulates a full-featured telephone, using VoIP to make and receive calls through the network
Softphones replace physical desk phones with software clients, enabling employees to take and make calls from any device with internet access—a key enabler of remote and hybrid work.
CTA Customer Premises Equipment & Unified Communications 2
What is the E.164 numbering standard and where is it used?