Microsoft launched its UC (Unified Communications) products this month with the intention of replacing the traditional PBX. But before it can get to a dominant market share position if it ever gets there at all, it's going to have to interoperate with existing telephony systems on the existing standards that are in place. Unfortunately for Microsoft, the current UC products will not be able to interoperate with the most commonly implemented patent-free wideband codec G.722 in existing high-end SIP phones. This means Microsoft's UC phones will be restricted to narrowband calling when it tries to dial wideband enabled IP phones from Cisco, Polycom, Avaya, Snom, Linksys, Mitel, Grandstream all of which use standardized G.722. Microsoft UC phones will instead go its own route and use its own proprietary wideband codec called RTAudio and a proprietary Polycom codec G.722.1 called "Siren".
I had asked Microsoft about G.722 compatibility during WinHEC in May and I got an answer when I got back home after the show and I was shocked to hear that it didn't support it. I spoke with members of the UC product team to let them know of my disappointment and argued from a practical perspective why Microsoft should simply add the royalty free standardized codec to their UC platform. What I got in response was how none of Microsoft's customers were asking for G.722 interoperability and how old and inferior the codec was. I told them that from my perspective as a former IT person, I would not be happy with this incompatibility and that it's unlikely that their customers would even know to ask about such a thing.
I contacted Polycom after the initial Microsoft meeting to see if their "HD Voice" branded wideband IP phones would support G.722.1 so that it could interoperate with the UC phones. It turned out Polycom wideband "HD Voice" IP phones only supported G.722 and G.722.1 "Siren" is only used in Polycom's high definition video conferencing products. I then had a conference call in June with Polycom CTO (and cofounder) Jeff Rodman to discuss how the world of Video conferencing and telephony don't interoperate at wideband. Jeff Rodman explained that the phones not only have limited processing capability but limited memory. While certain compression algorithms may be computationally feasible, they won't necessarily fit in the memory space of standalone IP Phones. This may be the reason that G.722 - while not as effective in compressing wideband audio at lower bitrates - is the only codec that is universally supported.
Fancier codecs like RTAudio and G.722.1 which produce smaller streams at the same quality level are more suited to high-end video conferencing end points and general purpose computers that have more than enough CPU and memory to handle the workload. So while G.722.1 and RTAudio may have better compression ratios with wideband audio streams of 32kbps, it may be too complex for dedicated hard IP Phones. While G.722 produces a less compressed 48 to 64 kbps wideband stream, the difference isn't as big when you factor in the 18.8 kbps of IP/UDP/RDP header overhead on a TCP/IP network. By the time header overhead is counted, we're really comparing 66.8 to 50.8 or at worst 82.8 versus 50.8.
So now that Microsoft has launched their Unified Communications product, I went back to Microsoft to ask for a status update. Unfortunately it was pretty much the same arguments I heard back in may and here is the official reply Microsoft sent me last week.
“From a customer perspective, we have not had any requests for adding this codec to our stack. Further, while the Polycom HD SIP phones support G.722, we haven’t seen large installations use this codec. From a technical perspective, 722 was first developed for ISDN video conferencing – it’s quite old. As a result, it doesn’t support the same level of resiliency to packet loss or use of bandwidth on the wire that more modern codecs like RTAudio provide. It’s critical that we provide our customers the best possible quality of experience with Office Communications Server 2007 and at this time we don’t see G.722 support as advancing that goal forward.”
As I told Microsoft in person, I don't have a problem with advanced codecs like RTAudio and G.722.1 but I do have a problem with lack of interoperability. At this point in time I think it would be fair to say that G.722 enabled devices absolutely dwarf Microsoft UC devices. Interoperability shouldn't be something that you only do when a large enough customer threatens to avoid Microsoft's UC products unless they make their products interoperable. Furthermore, I doubt Microsoft actually took a poll of its customers or advertises the fact that they can't do G.722 which is the only wideband codec support on all the other IP phones on the market.
Microsoft has made a lot of progress in recent years in the area of openness and I fear this is a regression to the old closed Microsoft. I actually have some high hopes for Microsoft's UC platform and I especially like the fact that you can set up your own web conferencing portal. I've deployed Microsoft's conferencing products all the way from Exchange Conferencing Server to Microsoft Live Communication Server 2003. I still intend to fully evaluate the new Office Communication Server 2007 but the lack of G.722 interoperability and the UC team's attitude towards this matter has soured things for me especially when they admit it's trivial for them to add G.722 compatibility. I think there is plenty of room for a product that can free us from the tyranny of proprietary PBXs but only if the liberator adopts open standards.