I may be wrong but the way I understand it is the IP Office Small office comes with either a 3 or 16 channel voice compression module. This means that you can use 46xx IP phones etc to connect to the box without the need for a license, as in reallity its the phone that is the license and that way their not cheap.
However if you are using software you need to purchase the ip endpoint license, otherwise Avaya would not be able to make any money from it as we would all use netmeeting instead of phone manager pro.
I dont think you can get around it, however in testing we found the voice quality of phone manager pro far better then that of netmeeting.