Hi Andrey,
You can add contacts when you use ICQ number and add @icq.com at the end.
In Office communicator go to Add a Contact
Chose Use an e-mail address or sign-in address
Type the ICQ number followed by @icq.com
Press Next, Choose the permission level.
That’s it.
I tested it on my computer
I am using Office Communicator 2007 and ICQ 6.5.
On ICQ I receive everything
Unfortunately I have a delay with approximately 15 seconds on my OC when messages are sent from ICQ …
BR