Force to use Lync Web App for conferences

If you have lync 2010 instaled on your system ,when you click on join conference URL it will launch your Lync 2010 client.What will happen some other organisation send you the link to join conference?you will not be able to join the meeting.
If you dont have Lync 2010 in your system you wil get below screen

 

So this will give you the option to join the meeting.But for such above case it is difficult because Lync default behaviour is like that.So if you want to force the use of Lync web app follow the below steps

simply add ?sl= to the meeting URL

Eg:https://meet.sipdomain.com/test/abcdefg34?sl=

The Lync Client will not launch and you can choose to run Lync Web App