Abstract

Siemens Enterprise Networks commissioned The Tolly Group to evaluate its optiPoint 400 standard, an IP-based telephone system that uses an Ethernet interface with a built-in, two-port Ethernet switch to deliver a wide range of functionality to the desktop over IP. Siemens asked The Tolly Group to evaluate the call quality and fetures of the optiPoint 400 standard versus IP telephones from Avaya Networks, Cisco Systems, Nortel Networks, Pingtel and Polycom, but since IP phones from Avaya, Nortel and Polycom required the use of proprietary IP PBX or IP gateway equipment that was unavailable to The Tolly Group for testing, only the Cisco and Pingtel products were evaluated head-to-head against the optiPoint 400 standard.

Summary of Test Report:

Siemens Enterprise Networks commissioned The Tolly Group to evaluate the voice quality, latency, and feature set of its optiPoint 400 standard IP telephone, comparing it against rival products from Cisco (7960G) and Pingtel (xpressa). The optiPoint 400, designed with a built-in Ethernet switch and support for both H.323 and SIP protocols, was tested to assess its suitability for toll-quality VoIP deployments over existing IP infrastructures, without requiring proprietary PBX systems.

Test results showed that the optiPoint 400 delivered superior or equivalent voice quality compared to competitors, achieving a PESQ score of 4.18 with the G.711 codec and maintaining acceptable quality even under heavy compression (G.723.1 codec at 6.3 kbps). The Siemens phone exhibited significantly lower end-to-end delay, outperforming Cisco and Pingtel by margins of 13% to 57%, respectively, under SIP scenarios. Additionally, its feature set outpaced competitors with capabilities such as protocol conversion (H.323 to SIP), web-based management, SNMP support, and unique self-diagnostic functions, eliminating the need for costly IP PBX systems for smaller deployments.

The report concluded that the optiPoint 400 is a versatile and high-performance IP telephone, delivering toll-quality voice over IP across multiple signaling protocols with minimal delay. Its ability to operate independently of proprietary infrastructure, combined with extensive manageability and feature support, makes it an ideal choice for scalable VoIP deployments, supporting both small office setups and larger enterprise environments as demands grow.

Key Performance Metrics – Siemens optiPoint 400 standard

• Voice Quality (PESQ Scores):

  • G.711 (64 kbps): 4.18 PESQ (toll-quality benchmark).

  • G.723.1 (6.3 kbps): 3.5 PESQ (fair, near toll-quality).

  • Outperformed Cisco 7960G in compressed codec scenarios (G.729a score of 3.44).

• End-to-End Delay (ms):

  • G.711 SIP scenario: 65 ms (lowest among tested phones).

  • Delivered 13% to 57% less delay compared to Cisco 7960G and Pingtel xpressa under SIP tests.

  • All delays were well below ITU-T’s 150 ms recommendation for acceptable voice performance.

• Feature Superiority:

  • Supported both H.323 and SIP protocols natively.

  • Only phone tested that could operate without requiring external IP PBX or SIP proxy infrastructure.

  • Provided advanced manageability features: Web-based admin, SNMP support, and self-diagnostics.

  • Supported 56 verified telephony features, surpassing Cisco and Pingtel in protocol flexibility and deployment ease.