As you can see, Cisco now has a substantial lead over Avaya. In fact, Allan says this is the biggest market share lead any #1 has enjoyed over a #2 since the days of the old AT&T.
If you feel like this snuck up on you, you're not the only one. Last year, Allan's measurement of the same metric had Avaya up over Cisco by almost 5 percentage points. Here's the market-share pie from Allan's January 2007 BCR article: 
Cisco gained a remarkable 12 points' share in less than a year.
At first blush, this looks really bad for everyone but Cisco. But there are a few things to note.
For one thing, you'll notice that Avaya has actually grown its market share slightly since Allan's January report. Siemens, too, actually picks up almost 2 percentage points in that time, and Mitel manages to grow its share almost exactly equal to its acquisition of Inter-Tel.
Another thing to keep in mind is that it's a little trickier counting IP-PBX stations than it was with TDM PBXs and key/hybrids. Allan explained that and a few other points in a note to me:
* The Avaya and Cisco PBX data includes their small system offerings, IP Office and UCM Express, respectively, being sold into traditional KTS/Hybrid customers.
* Nortel PBX data is exclusive of its BCM models, comparable in feature/function to most IP Office shipments and UCM Express [i.e., small systems]
* NEC PBX data is also exclusive of its IPK Electra/Aspire offerings, comparable in feature/function to most IP Office shipments and UCM Express
* Cisco, Avaya, Mitel, and NEC provided line station shipment data to analysts; Nortel provided system-only shipments, therefore, line station shipments were estimated; Siemens provided no data, therefore, line station shipments were estimated.
* No other PBX supplier market share was above 2%.
* Nortel PBX data is exclusive of its BCM models, comparable in feature/function to most IP Office shipments and UCM Express [i.e., small systems]
* NEC PBX data is also exclusive of its IPK Electra/Aspire offerings, comparable in feature/function to most IP Office shipments and UCM Express
* Cisco, Avaya, Mitel, and NEC provided line station shipment data to analysts; Nortel provided system-only shipments, therefore, line station shipments were estimated; Siemens provided no data, therefore, line station shipments were estimated.
* No other PBX supplier market share was above 2%.
So, given Allan's points about Nortel and NEC, the overall picture may not look as bad for them--and therefore, not quite as good for Cisco--as the figures make it seem. But no one questions, any more, that Cisco has taken the #1 slot, and there's little reason to envision them relinquishing it any time soon. Furthermore, these most recent Cisco and Avaya numbers both include the respective vendors' small systems, so we do have pretty much an apples-to-apples comparison between the top 2 market share leaders.
The conclusion I'd draw is that consolidation, which hasn't happened as quickly as a lot of people thought it would, will likely pick up in 2008. Note that in 2006, none of the 5 vendors who placed below the top 6 had less than 3% share. As Allan pointed out in his note to me, the current figures show that now, no one below the top 6 has above 2% share.
The other thing to look for on a graphic like this a year from now: Where will Microsoft appear?
