it is possible to communicate with the user who has lync (lync server).
Now we are launching the openfire server and want to communicate with customers what lync have.
Out of the box, no.
You’d have to write your own plugin to do so.
There was a xmpp-lync gateway at some point (made by MS i think). But it was many years ago and as Lync is replaced with Skype for Business (and it will be replaces with Teams) i doubt MS is still developing/supporting it. You may search the forums, but it most likely won’t work anymore.
Any XMPP based server can communicate with MS Lync/Skype for Business Server IF the Lync/Skype deployment contains an Edge server. This is a server that resides usually in the DMZ and provides the federation to XMPP servers. The Lync/Skype Front End servers (located in the private network) actually have the XMPP gateway service. The XMPP is forwarded to the Front End servers from the Edge servers. This type of federation can use TLS, SASL, and Direct Server Callback depending on how you want to communicate.
I actually have this working with Skype for Business 2015 and current OF version. Having some subscription issues but users are able to chat with each other. I will be posting the issue in detail later today.
Do the S4B users experience issues seeing the presence of the OF users? Sometimes it seems to take a long time for the S4B users to see the OF users’ presence. If the OF users log off then back on then the presence subscription is updated and it seems to work fine.