Hi,

as mentioned in the subject we configured the Lync<>Skype federation and so far everything went well.

The only thing that is not working is to start a call from Skype to Lync, Skype is saying "no answer". IM in both directions and a voice call from Lync to Skype is working.

Any idea?

Hi,

Please check the event log on Lync Edge and front end server.

Please also enable logging tool to get report for troubleshooting.

http://technet.microsoft.com/en-us/library/bb936621(v=office.12).aspx

I would like to confirm if your external user call work properly.

For your reference, here is a similar case that was caused by missed firewall rules from Edge server to the Internet:

http://social.technet.microsoft.com/Forums/lync/en-US/88c8c94c-b968-4164-9537-d0b955fb86c9/lync-skype-audio-calls-not-working