Lync Online is available in three stand-alone plans (Plan 1, Plan 2 and Plan 3) - as well as part of the Office 365 packaged plans (the P and E plans). See the below chart for more information on which Lync Online plan are included in which packaged plan

(click the picture for the larger image)

 See also

• "Lync Online meeting limit increase in the works" - link: Microsoft intends to increase the supported meeting participant limit from 250 to 1,000