Join conference via Lync call rather than Call Me At

Question

We have deployed Lync Server 2013 and are just beginning to deploy it in small doses to portions of the organization.  We are using a combination of Lync 2010 and 2013 for clients.  This post is regarding the Lync 2013 client.
We use Lync with Cisco telephony via Remote Call Control.  We do have PC-to-PC calling enabled in addition to RCC (the Telephony setting in Lync Control Panel on the user accounts is "Remote Call Control").  We are not using Enterprise
Voice.
After deploying Lync as simply an IM + telephony client, we have begun to focus on rolling out the web conferencing functionality.  In doing so, we have noticed strange behavior which I describe below.
Let us assume that someone other than me creates web conference by selecting two people, including me, in their Lync contacts list in the client, right clicks, and selects "Start a conference all" and then chooses "Lync call".  I
see a Lync toast notification appear, inviting me to a conference.  It says the conference organizer's name and says "Conference Call".  If I click the toast to accept the conference, my Cisco telephone extension immediately begins to ring. 
In the meantime, in the Lync conference in the client I see "Join Conference Call" and "Other".  If I answer answer my telephone extension or push the Join Conference Call button, I am successfully joined to the Lync audio conference
and can speak with anyone else that joined the conference, whether they are using Lync audio or Cisco telephony.
The problem is that there are cases where we want to do a video conference.  I am aware that can only be done if using Lync audio rather than the Cisco telephony.  I can disconnect from the conference call by hanging up my Cisco extension. 
When I do so, the Lync conference in the client shows a notification that gives me the option to rejoin the conference.  The "Rejoin" button has a down arrow, and if I expand it I can select "Rejoin using Lync Call" and if I do that
I can now see others' webcams and can share my own webcam with the conference.
My question is: how can I elect to join the conference in the first place with a Lync call rather than having the Lync conference bridge dial my Cisco extension?  There does not seem to be a way to do this that we can get to work.  For instance,
I mentioned that after I have clicked the Lync toast notification after being added to the conference and my Cisco phone begins ringing that I see the options "Join Conference Call" and "Other" in Lync client.  If I open the Other
options, I see "Join using Lync Call" as an option.  If I select that option, my Cisco phone answers the call and I am joined to the Lync audio conference with my Cisco phone and not Lync audio.
Please note that I already checked the Phone section in the Lync 2013 client options and the box "Before I join meetings, ask which audio device I want to use" is checked and the "Join meeting audio" drop-down box is set to "Lync".

Answer 1

Sorry, I misread your question and now see that I did not pre-emptively answer it.  I just tested it and unchecked the box "Before I join meetings, ask which audio device I want to use" and made sure "Join meeting audio" was set to "Lync".  Even
after doing so, the behavior is the same:  the Cisco phone automatically rings and any action to join the conference results in the Cisco phone extension being picked up.
Basically, it seems that if you use that "Start a Conference Call" option from the Lync contacts list, the Lync preferences set in the recipients' Lync clients are ignored.  If you schedule a Lync conference via Outlook or people use the Lync meeting
URL in their Internet browser, it does respect the preferences correctly.  It seems like it might be a bug.
I would be interested if any other Lync Server 2013 users with Lync client 2013 and using RCC could repeat my tests and see if they have the same issue.