Cell phone service questions.

[John Schmidt]

It's my understanding that there's a couple networks(Verizon for one maybe?) that regardless of whether your phone is unlocked, that phone only works on Verizon and 1-2 other systems. Might have something to do with the phone only works with that system's sim card even if unlocked.....I think. I find myself lacking when it comes to a working knowledge of cell phone mysteries & systems. Reason for the questions is my current LG-G2 is developing some dead spots on the screen, making it difficult to dial a number if it's not already in my contact list. Eventually I'll not be able to access that either so need to make a change, possibly a new one but remains to be seen.

[hubcapsc]

You might be thinking of the difference between CDMA and GSM...

https://www.pcmag.com/article2/0,2817,2407896,00.asp

https://en.wikipedia.org/wiki/Code-division_multiple_access

https://en.wikipedia.org/wiki/GSM

I use ATT, so I'm GSM. I just went from flip phone to smart phone,
got an Iphone SE new for $240 on Amazon. It is real small, and
takes great pictures  ...

-Mike

[Robert]

ATT and T Mobil is the same and use GSM. Verizon and Sprint, US Cellular use CDMA for their voice services. Most of the world uses GSM. 

When I bought my I phone it was a T Mobil phone that I use on ATT. Its the network technology that makes the difference, but there are phones out there that can use any of the Carriers. Locked or unlocked you cannot interchange the network unless they use the same technology.

 The iPhone X A1865 is considered the global phone as it works on both GSM and CDMA networks. This phone is also available as a SIM-free factory-unlocked version at Apple Store and the cost is about the same as one that doesn't support both systems.