I've always been very happy with my 1520 and since installing the latest Windows 10 Technical Preview I can't see myself wanting to go back to any other operating system. My problem is, I really need a VOIP app that can run in the background to keep a permanent connection with my 2 SIP accounts. I've looked at the Note 4 and iPhone 6 but they don't compare with my 1520 running Windows 10. Is there any sign or hope that Microsoft will ever support apps running in the background? I would be so pleased to be able to stick with the 1520.