Martijn
I use mullvad.net and have never had any issues with them. They are easily reached over email as well. OpenVPN configuration files and PPTP tunnelling are both available, so I think you should be able to get it to work on a Windows phone.
Mark Dain
Still looking? A lot of people talk highly of Private Internet Access. I'd go for a VPN provider who accepts Bitcoin; they're probably more likely to take your privacy seriously. Otherwise if you're just looking for a U.S. IP address, a SOCKS proxy (via SSH) might be enough; you could get a cheap server from Linode for this.
💻 Anatasof
I'm currently using hide.me vpn service. I've used some vpn service on my current phone (a windows phone) but ikev2 seems to work more stable than other native setup like LT2P with IPSec. Lot of people talk highly of PIA, yes, which so tempting for me to try it. But again, as a windowsphone users, it's kinda hard for me to find PIA review on windowsphone. :(