What softphones do the call control for the LH250 and LH255 answer?

Great question!

Easy answer:

Skype for Business.

Yep, that’s it!

So far, no other softphones work for answering calls with the LH250 and LH255, not even the free home-user version of Skype.

However, even if you can’t answer and end calls, the volume and mute buttons on the cord will still work for you.