This is more of an annoyance than a problem. I've got Pidgin set up to work with Lync. It works fine, but in the conversation windows, the other user's name always appears as "sip:firstname.lastname@example.org". Is there any way to change this? Get rid of the "sip" part or have Pidgin grab the user's display name directly from Lync?
Yes, add the partner to the Buddy list. Then he gets an alias automatically or you can set your own.