Its called a benchmark, used by surveyors as a known point from which to take readings. We had a benchmark on the edge of of our property in the town where In grew up. It was a square, white marble column, like a truncated obelisk with the point cut off to make a 4" square flat top, buried at the roadside and standing a couple inches proud of the grass. It had a cross with a dot in the middle, and a geodetic ID number engraved on the top.
Nailed it with the lawnmower once or twice. That'd really put the Fear in you.
That's good to know. I've pretty much always been a TMO customer aside from a couple of years when I was with Cingular around the time of their buyout. They were pretty open back then.
I buy all of my phones carrier-unlocked, and have never had a problem.
Potential pitfalls are if the IMEI is blacklisted, which could happen if the phone is reported as stolen, or if the radio deck isn't compatible with your carrier's network.
In the US, the AT&T and T-Mobile networks are pretty open, and you just need to pop in your SIM card. I don't have experience with Verizon to know if you can bring your own device or not, but I imagine as long as the phone can work with Verizon then its probably just a matter of visiting a store to have it activated.
NileRed (ok fiiine, NileBlue) would like a moment of your time:
https://youtu.be/0aGNAxN5Z-o