On website community.office365.com you can find website with information about problems with Lync-Skype connectivity.
You will find there information how to resolve common problems like:
- A Lync user does not receive a contact request from a Skype user
- A Lync user removes a Skype user, but the Skype user can still see Lync user’s presence and send IMs
- When a Lync user calls a Skype user, the call sometimes fails
- Office 365 Small Business customers have External communications turned on, but can’t connect to Skype users
- Skype users signed in with a new Microsoft account notice a delay of several minutes in seeing the presence status of a newly-added Lync contact
You can find there answers on Lync-Skype connectivity problems, and peruse a bevy of tips, tricks, and workarounds for people who are having trouble getting connected.
All information are available here: