Technical depth
Check depth on VoIP and SIP trunking, PBX platforms such as Cisco CUCM, Avaya or 3CX, QoS tagging, DHCP option 66 provisioning, and BICSI cabling standards.
Evidence to listen for
- Explains the physics or mechanism behind their work, not just the tooling
- Names the standards, tolerances, and constraints they designed against
- Can defend a design decision under follow-up questions
- Distinguishes what they personally engineered from what the team delivered
Five-point scoring guide
Cannot explain the fundamentals of their own stated specialism.
Knows the vocabulary but not the underlying mechanism; struggles under follow-ups.
Solid working knowledge for the role; depth thins out on edge cases.
Strong command of the domain; explains trade-offs and defends decisions well.
Names codecs, jitter buffer settings and dial plan logic precisely, and explains why QoS marking failed across a specific carrier handoff.