So, Let me make a few points. I have just completed a fairly exhaustive study of the major carriers and done some testing to back up my thoughts/suspicions.
- I've had Sprint (spectrum) in one form or another since 1993 (out of KC).
- Sprint used to have very poor customer service, unless you were business--which we are, but is now much much better IMO
- We currently live in an area that has poor to very poor reception.
- All the carriers will work in our area, but with varying levels of throughput/quality
- We update phones every 2 years and have ONLY had Sprint phones on our network.
- Many networks have bands/coverage that are specific to their brand of phones (or full-band unlocked phones YMMV)
- Just because the phone WILL work on another network does NOT mean that you have full area coverage or coverage at the highest speeds/quality
- Many new technologies have been implemented on some networks that radically change the quality/reliability of the network, Old phones may not
- I've traveled coast to coast, internationally and all-over the country with my phone.
- I can only address Sprint, but in the last 5 years, my sprint coverage has been great, and with tower sharing, phenomenal. I'm convinced that most people who complain about sprint coverage in the last 2 years are either using old equipment, cheap equipment, less than full band coverage (other carrier equipment) or have really high expectations for cellular coverage
- Sprint international phones (and iPhone 6/7) work great overseas but with slow data speed (without paying for hi-speed data)
T-Mobile currently has better deals on service, phones and overseas coverage. Really, look at the 55 and over with International plus service.
- T-Mobile is now outgrowing the competition
- T-Mobile has the best options for international use IMO free or 'plus' level paid coverage. Plus full GSM/LTE bands gives better options for coverage/speed
- I would NOT use T-Mobile with another carriers phone/unlocked phone unless I had full spectrum/brand coverage for T-Mobile. I would NOT use an 'old' T-Mobile phone on T-Mobile either.
I purchased a new, full-band phone to test T-Mobile coverage in my area (across a 100 mile journey) and compared it to an IPhone 6 (sprint) on T-Mobile Sim.
I further compared my current Sprint coverage to the T-Mobile coverage (east coast NOVA)
- The Sprint coverage (which is dual tower shared with T-Mobile) is slightly superior to T-Mobile (not dual tower). So, maybe 95% vs 92% (decent coverage with 4g hi-speed data)
- The T-Mobile coverage was equal to or higher than Sprint where coverage was available. Significantly higher data speed (10x+) in some areas.
- The T-Mobile band 12 LTE coverage was absolutely required for adequate service. Do NOT use T-Mobile without band 12 extended LTE.
Further, T-Mobile will loan/rent or sell you a micro cell spot for your home if the coverage is weak. This is huge for some folks (like me). T-Mobile is very Wi-Fi calling friendly.
T-Mobiles 55 and over plan is really attractive.
T-Mobile current spectrum (**band 71 is deploying now): bands: 2, 4, 12, 66, 71** freqs: 1900, 1700 def, 700 a, 600
If you're thinking about switching for the price, the deals and the overseas coverage, then at least give the carrier a good look by using a new, fully compatible phone vs an old craigslist special that won't take advantage of available bandwidth etc....
BTW: Costco is selling a very nice T-Mobile Moto phone for about $250 in stores. It was a very nice phone and quick. A great alternative to a $700 IPhone or S-phone. Again, YMMV.