I work for a technology company that supports varoius clients.  We also support the Plantronics needs and supply them with new headsets, bases, and more.  I was at a client site today and they bought just a new headset not a new base for their new receptionist.  Claiming the old one was unsanitary and so forth, an issue easily remedied with some lysol and disinfectant but nevermind that.  This new headset is slightly a newer model than the original.  The base is a CS50, and the newer headset is also labeled as a CS50.  But for the life of me I can't get it to sync.  I have reset and repaired the device innumerable times and everytime the new headset won't work.  The green light likes to flash over and over repeatedly and give me three audible beeps when I press the call button.  I called Plantronics support, they said it may be a battery or may be dysfunctional.  I say dysfunctional.  A battery seems unlikely since they've had it only a week and we just hooked it up yesterday.  What's interesting is that the old headset synced up like a breeze.  Followed the plantroncics directions just like I did with the first and everything went great.  Got dial tone, automatic phone pick upper worked, and so forth.  Not sure why that is.  I wondered if maybe there wasn't some small pairing incompatibility with an older cs50 base and a newer cs50 headset.  I haven't read anything to this effect yet, but thought I'd post here and see what comes back, thanks.