Make sure you have updated to the compatible version of software for your firmware version. Older versions of software are not forwards compatible wheras the newer versions of software can connect to older versions of firmware
Check the version of the console software you are using then use the Check for Updates tool in the Help menu to see what the newest console software version is. Likely you just need to use a newer version of the console software to find it again.
The Chat 50/60/150/160 are general purpose speakerphones. The Chat 70/170 has special firmware to allow you to pick up and end calls in Skype For Business from the device using the Call Control button on the unit. The 70/170 still works as a general ...