Here is the page in the USER Guide about it:
https://admhelp.microfocus.com/alm/en/12.55/online_help/Content/UG/t_im_chat.htm?Highlight=skype

In summary:

1) Add a site parameter ''SKYPE_INTEGRATION_ENABLED'' from Site Administrator/site configuration tab and set to ''Y'' (default value).

2) Cycle the HP Application Lifecycle Management service

3) Your collaborating QC users must be assigned to teh SAME QC project and have their email addresses populated in the User Properties.

4) The users must also be signed in to the IM tool (Skype)

You should now see a green square next to the user's name (on the defect ''form'' if they are ''author'' of a defect for instance) to indicate they are present/available in IM.

You need to go to the [Module] Details button (for example ''Defect Details'' button) to select participant names, select a participant(s) and start/send an IM.

You also need to make sure you have supported version of Skype:

Skype Business version for team collaboration

Minimum QC/ALM version 12.55

Lync 2013 (OLD NAME)
Skype for business 2015
Skype for business 2016