ROK Mobile for T-mobile Nexus 5 (or any tmo phone)
Posting this simply because it took me forever to find this info, and ROK support kept telling me to update PRL and Profile...not something you can access on a GSM-programmed phone (at least I can't, not even on Stock rom).
Got my phone activated yesterday after waiting a week for my SIM. Was using my FreedomTalk VoIP minutes on my Nexus to talk to support so when they said to reboot and everything should be set, i just hung up on them and rebooted. Everything worked but data. Gave it a day, still no go. Called and they said we needed to manually reprogram the phone...so I needed to call back from a different phone (not possible at the moment). I told him I couldnt and he said to shut down, turn on after 60 seconds, update PRL and Profile, and see if that works. Obviously it did not. After much Googling I found this article on ROK's own site and it resolved my issue of not having data services.
Follow that and boom, data will start working immediately.