If you hover over the handset icon for a contact, you see all of the ways to connect to a user in Lync. Lync call, Voicemail, and phone numbers, etc.. If a user isn't voice enabled, then the phone numbers are irrelevant. They shouldn't be visible or clickable to non voice users.
When a user has set the forwarding to a PSTN/mobile number, (s)he can possibly be reached even if the presence shows the user as "offline".
I think the presence should show the forwarding status (just like Skype does, btw) for example as "offline with call forwarding".
The contact card should also show some additional details (e.g. "forwarded to xxx") to users in the workgroup/friends and family groups.
If you right-click on a lync window there is an option to keep the window 'Always on Top' of other windows. I'd like to see that be an option to set so that all active calls default to this window behavior. This should reduce hang up delays when using a PC for Lync calls where there are several windows open and you are forced to search for the active lync voice conversation to close it.
It would be quite handy to be able to dock the dial pad when in a call instead of repeatably having to hover over the phone/mute button. I know you can use the number pad on a keyboard but sometimes button presses are not registered and you then have to find the window to get the dial pad up.
When you click the button to call someone in Lync, and choose the "New Number", you can enter a new number and escalate the IM conversation to voice. But it doesn't store that number anywhere. It would be nice if it could do that.