[Nexus 9 Q&A, Help & Troubleshooting] oldblue910:
Guys, I might be able to shed a little light on this.

First off, even though Google initially mentioned CDMA and LTE support for Verizon, Sprint, and USCC bands, none of those carriers were EVER mentioned by name as being supported for the Nexus 9 LTE. The only places that mentioned Verizon, Sprint and USCC in reference to the Nexus 9 LTE were tech blogs because the radio has all the support at a hardware level. Further, Google has removed all references to CDMA support in the official spec listings on their Nexus 9 web pages.

Next, don't bother trying to use a Sprint or US Cellular SIM card in the Nexus 9 LTE. While, yes, it supports those carriers on a radio level, Sprint and USCC only use SIM cards for LTE and their networks require SIM cards to be tied to a valid device MEID. You can't just swap Sprint or USCC SIMs between devices at will like you can on GSM carriers and Verizon. If you take a Sprint or USCC SIM out of one device and put it into another, you'll have to call the carrier and have them associate the SIM card number to your new device's MEID. Since the Nexus 9 LTE isn't in either carrier's database as an approved device, they won't be able to do that. So, in short, you're never going to get the Nexus 9 LTE to work on Sprint or USCC unless those carriers whitelist the device. Simple as that.

Now on to Verizon...

Verizon is the first truly open CDMA network in the US. They do not discriminate or ban devices on a network level because legally they can't. ANY device that supports CDMA 800/1900 and LTE band 13 will work on Verizon assuming the software knows how communicate with Verizon's network properly and the device has an active SIM card. Now, Verizon does whitelist IMEI numbers in their customer service activation system, but you can get around that by using a different device's IMEI as we all know and get a SIM card activated that way.

So, if you're putting an active Verizon SIM card into a Nexus 9 LTE and it's not getting onto the network, that means one of two things:

1. Verizon is actively blocking the device. While this is certainly not out of the question, I'd be really surprised if this were the case. That is patently illegal for Verizon to do and it doesn't seem like it would be worth the time and hassle for one tablet that very few people even own.

2. HTC, Nvidia, or whoever wrote the radio firmware, specifically put something in the radio firmware to block Verizon SIM cards. This is the most likely scenario, but the question would be why? I can think of two plausible explanations:

One would be that there was some kind of hardware problem found with the radio that was causing some kind of big problem on Verizon which caused them to just disable the radio if a Verizon SIM is in the device. Another scenario is that Verizon asked Google or HTC to not allow the Nexus 9 to connect to its network, for whatever reason.

I'd say chances are well over 90% that this is something in the radio firmware that is actively blocking Verizon SIM cards, and who knows if it'll ever get changed in a future radio update. For now, though, it looks like you're pretty much stuck with AT&T or T-Mobile.

The removal of CDMA from the official specs says to me that either Verizon, Sprint, and USCC have no plans to carry the Nexus 9 LTE in the future, or that Google, HTC, and Nvidia still have some hardware or software bugs to work out in the radio before they're prepared to get those carriers on board. Time will tell what happens, but the lesson here is to not buy an unlocked tablet for use on a CDMA carrier, even if it supports that carrier on a hardware level. While the winds of change are blowing against the traditional US carrier business models, the CDMA players still aren't ready to embrace BYOD yet, and we're probably still a few years off from that. Once CDMA goes away and everything is on LTE, this will all hopefully become a complete non-issue.