Skype for Business - Free

This version installs using an MSI file and installs as a service so it works with all logins, even without login if you are using a USB phone.

• Download Skype for Windows – Business version (with MSI)

Testing, thanks Nicolas

• Related info:
  Making Dlink DPH-50U Adapter & Skype A System Service - Skype Community

Testing USB Phone AA2610 D700 for XP or older Windows.

Videk USB VoIP Phone AA2610 4401 - PC World Business Online Store UK - Buy The Best Deals Online.

aa2610 - Google Search

Ebay

$2.25 G-Trans Skype USB Phone AA2610 In Package White. on eBay.ca (item 160397575551 end time 27-Jan-10 14:23:28 EST)