Abstract

Tolly Group Report #202110 (January 2002) validates NEC NEAX 2000 IPS IP PBX, BlueFire 720/730 Layer 2/3 switch and BlueFire IX5010 router for end-to-end VoIP quality of service .

Baseline voice quality. With no congestion or QoS the IP-to-IP call path scored PSQM 1.84 and estimated MOS 4.38, both at toll-quality levels.

Severe congestion without QoS. Injecting 120 Mbit/s of background traffic oversubscribed the Fast-Ethernet port by 20 % and the T-1 WAN link by 100%. PSQM rose to 5.63 and MOS fell to 1.26, indicating unacceptable voice quality.

Congestion with NEC QoS enabled. Activating strict queuing on BlueFire switches and priority policing on IX5010 restored voice clarity to PSQM 1.78 and MOS 3.98, essentially matching the baseline even under the same oversubscription.

Infrastructure baseline. Core VoIP tests that excluded handsets showed the switching and routing fabric alone maintained MOS 4.38 at rest, dropped to 2.35 under congestion without QoS and bounced back to 4.38 once QoS was applied.

Conclusion: NEC’s NEAX 2000 IPS, BlueFire 720/730 and BlueFire IX5010 preserve toll-quality voice during heavy LAN and WAN congestion when their built-in QoS features are enabled, proving they can deliver predictable end-to-end VoIP quality in converged networks without sacrificing user experience.