Verizon Communications' Verizon Business division now guarantees the quality of VOIP (voice over Internet Protocol) calls on its global VPN (virtual private network) service.

Businesses are adopting VOIP for cost savings and for future capabilities, but as their voice traffic shifts from traditional dedicated, circuit-switched networks to a data network, it takes work to match the expected quality of a call.

At the FutureNet trade show in New York, the carrier introduced a service-level agreement (SLA) for customers of its Private IP service that measures audio clarity on a standard scale. The Mean Opinion Score (MOS) SLA uses a quantitative standard for audio clarity from the International Telecommunication Union (ITU) that measures the end user's call experience.

The SLA says the customer's average MOS performance won't drop below 4.0 on the ITU's 1-to-5 scale if they put voice on the top level of priority. That's a higher standard than most service providers use for SLAs, Verizon claims. The carrier will use probes on the network backbone to take regular measurements of audio clarity, said Danellie Young, director of IP and Ethernet services.

Also Tuesday, Verizon Business rolled out Network Assessment with Voice, a service that gives network administrators information to help them ensure call quality on their networks. The carrier will go in to any enterprise, including those that don't use Verizon Business as a carrier, and put monitoring software on desktops, typically for 45 days, Young said. The service, based on technology from network management software vendor Centrisoft, gathers information about how voice and other applications perform. The information can help enterprises fine-tune their VOIP call quality and prioritize traffic types to allow for good voice calls, among other things. The customer can turn to Verizon Business or someone else to carry out subsequent changes.

Network Assessment with Voice is a new component of Verizon Business's Application Aware suite of reporting tools, which the carrier introduced last year in conjunction with Centrisoft.

The call-quality SLA is in place now for all customers of the Private IP service. Network Assessment with Voice is set to become available later this month. It will be priced starting about US$5,000 for one to three sites, up to about US$20,000 for 50 sites.