[Moto G5S Plus Questions & Answers] internetpilot:
No, it's a carrier independent unlocked phone that I bought from BestBuy.com (because they offered the best price for the 64gb version through a Cyber Monday sale). Except for the iPhone (and maybe the newer Samsung models), Sprint phones don't have removable SIMs -- they're built-in to the phone making them a special Sprint-only phone. That's the way my Samsung Galaxy Note 2 was. After my Note 2, I bought an unlocked Google (Motorola) Nexus 6 and used a SIM to use it on Sprint (and had access to APN setting as soon as I activated the phone), but that SIM isn't compatible with the G5S+ even though they're both Motorola phones, have the same radios, etc. I'm pretty sure my current problem is the SIM, but I don't think it's unsolvable. I just think I'll need to root and mod or ROM the device to get access to those settings. I know this is one of Sprint's newest SIMs (they have like 22 different SIMs), so I'm sure this is just another attempt by Sprint to lock down unlocked carrier independent phones on their network to help reduce excessive roaming (on Verizon towers) which costs Sprint money.

I've been on Sprint for like 15 years. The only reason I stayed on them is because the others aren't really any better, and Sprint is the only one who truly offers unlimited everything (which is really good to have for a family of six). Starting like 3 years ago (when Sprint and Samsung abruptly abandoned the Samsung Galaxy Note 2 rather early), I refused to buy Sprint locked-down phones because they require to sign another 2 year contract commitment. Whereas right now if Sprint ticks me off (like they did a couple of years ago when they sent me a $500 bill for "free" international roaming), I can just immediately drop them and move on with no penalty and even take my phone with me.

This is the first Android phone I've owned that I haven't immediately rooted. I even rooted all my family's locked Sprint phones. There just isn't much support for this phone from 3rd-party devs (yet or maybe ever since it's just a "special edition" upgrade?), so I really want that OTA Oreo update in place before I root it. I came pretty close to immediately rooting this phone, but then decided not to when saw some people had problems getting it back to stock enough to take the OTAs from Moto. I actually like the Moto Android (along with a heavily themed Nova launcher) experience enough to not feel the overwhelming need for a custom ROM, so about the only thing I really want root for is to get a better camera app (preferably Google Camera), wifi tethering, and Titanium Backup. I'm even getting used to the stock Moto camera app, so I'm not really feeling the pressing need for the Google Camera as much. I wouldn't mind getting LineageOS 15 on here, but there isn't an official version and it doesn't seem very stable yet on any device. I tend to keep my phones for a while (three years for my Nexus 6 and Note 2), so I tend to outlast most 3rd-party dev ROM support, which is why I tend to just go with LineageOS (and before that CyanogenMod) which doesn't just vanish one day like individual dev ROMs do. We'll see what happens. Hopefully this phone will start seeing more developer activity. I was originally going to get the Moto G5+, which does have a lot more dev support, but considering how long I tend to keep phones, it didn't make sense not to buy the latest/greatest version.

I'm sure it will all eventually work out. Worst case scenario is that during a European vacation next Summer I won't be able to take full advantage of Sprint's free low speed international data roaming and texting, but even then I can always just grab a local PAYG SIM and use it.