As you know, managed IP services have been inching farther onto the enterprise premise.  Some carriers, such as Equant and Infonet, offer managed VoIP services that not only include converged voice and data transport in the WAN, but managed IP telephony services on the LAN, as well.

As wireless LANs begin carrying VoIP traffic, the finger-pointing has the potential to get ugly. If you begin to experience poor-quality VoIP calls, whose issue is it? Does your IP telephony contract allow for a WLAN access point to be attached to the configuration, potentially with 802.11 handsets hanging off of it?

If not, who's in charge of figuring out the call-quality issues that the roaming wireless caller is experiencing? After all, degradation could have to do with the wireless access medium or mobile handset - but it could just as easily be a wired LAN or WAN issue.

Given that VoIP requires more real-time troubleshooting and resolution than data - let's face it, who wants to wait for people to analyze reports and correlate trends while on the call - there's work afoot to create a performance management architecture for VoIP. It involves special agent software getting embedded in the equipment that sits in the VoIP calling path. The agents report, in real time, on packet loss, discard, latency, and jitter and signaling issues.

In the case of wireless, these agents would be in your 802.11 phones, access points, WLAN switches and in your wireless monitoring probes and analyzers. The agents are also in the wired LAN and WAN gear that your service provider provides, including the WAN gateways, IP PBXs and so forth.

If you need to troubleshoot VoIP calls - or want to make sure your managed-services provider is able to - you might wish to ask about support for this monitoring capability. A company called Telchemy, which makes such software agents (dubbed VQmon) and collection software (SQmon) is one company selling agents to network equipment makers. Telchemy's technology has yielded some VoIP QoS reporting standards, such as the IETF Real-time Transport Protocol Control Protocol Extended Reporting (RTCP XR) protocol and ITU QoS reporting protocols for the H.323 and Megaco signaling protocols.

Another company in this space is Psytechnics, whose software has become ITU-standard for intrusive voice-quality metrics.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.