(Test and Measurement World Via Thomson Dialog NewsEdge)

After years of languishing in the laboratory, voice over Internet Protocol (VoIP) has started to achieve a respectable installed base, and this is prompting test equipment vendors to focus more energy on addressing the needs of VoIP field testing. Test equipment introductions are now offering more portability, preprogrammed test suites, and expanded capabilities.

Several factors have converged to promote the growing interest in field testing, according to Jason Steele, product manager for IP diagnostics at Tektronix. "VoIP test is starting to go beyond lab validation and development," said Steele. "The specs have calmed down, so requirements are more stable, and large-scale services are being deployed, so the need for field testing has increased. Customers are asking, 'Now that it is out of the lab, how do I get it to provide quality service?'"

The needs of the field test engineer are different from those of the laboratory test engineer in two significant ways, Steele noted. One is that field testing demands portability, typically implying battery power and compact form factors. The second is that field testing typically needs to be less exploratory in nature. Unlike the laboratory test, which seeks to probe the limits of a design, field test focuses on verifying proper operation and on troubleshooting problems. "You need a lighter feature set compared to laboratory equipment," Steele said. "You still need measurement tools, but features such as load generation might only need to handle five to ten calls versus thousands of calls in the laboratory."

A number of field-oriented tools have become available. The Performer series from RadCom, for instance, includes ruggedized, portable VoIP tools with internal storage to allow later lab analysis of field data. Tektronix makes the Spectra and Spectra2 protocol-analysis tools in portable form, as well. Agilent Technologies and Spirent Communications both offer handheld units. Agilent's FrameScope Pro includes traffic generation and quality of service (QoS) measurement capabilities. Spirent's Tech-X Plus offers built-in diagnostic tests for common installation problems.

Portability is essentialBecause portability is a key issue for field use, some companies have elected to create software-only tools that work with a laptop computer, helping keep the field engineer's toolkit to a minimum. Tektronix, for instance, offers its Spectra2 tool in a software-only edition, Spectra2 SE. Similarly, Touchstone's WinEyeQ VoIP monitoring and analysis tool is software-based. Both depend on the laptop computer's LAN port for connection to the network under test.

Automation is also an issue for field use. "Ease of use is becoming a key point," said Steele, "and anything you can do to simplify the testing job is appreciated in the field." He added that by automating key test procedures, vendors are able to free test engineers from having to become experts in programming the tool.

The main questions that VoIP field test tools must help answer about the network, according to Steele, revolve around the QoS that a VoIP installation is offering and its ability to blend with traditional telephony. "Nearly 95% of calls still traverse the traditional TDM [time division multiplexed] network, so tools need to examine the bridge across the two types of network." The Spectra2, for instance, now supports protocols such as BICC (bearer independent call control) to address this need.

Field needs continue to evolve, however. New VoIP installations are aimed at offering more than phone service. IP video is one application that is gaining a lot of attention, and most of the VoIP tools now address the requirements of these additional media, as well. And the perfect mix of tool capabilities has not yet become clear. With large enterprise-wide VoIP systems beginning to be deployed, there has been an increasing demand for tools with the right level of complexity.

Steele noted that there is a need for a tool somewhere between one aimed only at installation testing and one with the full capability of a laboratory tool. "Installing in an enterprise is a big effort," he said, "and you need to be able to track down some large-scale effects."

To meet these evolving needs, test equipment vendors are paying attention to their customer's requests. "A lot of our tools are driven by customer demand," Steele explained. Vendors will continue to improve their VoIP field test tools as more installations arise and other technologies, such as wireless, converge with VoIP.