Mark,
I cannot tell you how much I appreciate your rare and insightful comments about Windows Messenger (WM). Valuable warnings of this kind are understandably difficult to find on the Microsoft Website, or anywhere else for that matter. The restrictions you describe are probably the reason that WM gets so little mention on the serusers list.
I visited the Microsoft website describing WM, and all of the WM documents I find are dated 2001, as if Microsoft has abandoned the WM product, which I don't think is really the case.
The documents did not mention any plan for me to pay a fee for WM use, with or without whiteboard and IM service. The site makes WM appear 100% free. Can you please direct me to a website or a phone number where I can find out the amount and conditions of such WM charges?
During my startup phase, while I am evaluating the viability of my tutoring business model, it is probably acceptable for me to pay WM fees to Microsoft, and to restrict myself to the uPnP routers required by WM. But over the longer term, both of those limitations will present a serious problem, just as you have suggested. Microsoft's failure to include STUN support in WM is a serious error which limits its deployability.
thanks for your help,
Michael