Go to the converter here
Skype for Business does not allow users to easily export contact groups for import into Cisco Jabber.
Right click on your Skype group header and click Copy
Open Skype To Jabber Exporter in any browser
Enter the group name and paste the copied group contacts into the contacts field, then click Add (Repeat this step for each group)
When you finish adding your groups you can copy the generated XML yourself and save to a .xml file locally, or click Export to download an XML file named "SkypeContacts.xml" with your converted groups and contacts
Open Jabber and login with your account, open the importer, choose the xml file we created or downloaded, then click import
Jabber will start importing your contacts and will inform you when finished