(07-02-2021, 02:09 PM)Nutmeg Wrote: thanks @rocket2nfinity When we signed up with US Mobile they said the White card was for GSM and the Black Card was for CMDA, so we were using the white card. Perhaps the black card would work. We did not try that.For the first time since I received my Pinephone 10 months ago, it finally works as a phone at my rural homestead and home in Idaho using my new US Mobile white SIM card.
Previously, my Pinephone only worked reliably in larger towns and cities an hour's drive or so away from home.Here's my background story and information. Though lengthy, it might motivate other Piners to keep trying different providers, particularly in rural areas, or possibly understand a few of their own peculiar and similar experiences and problems. Sadly, the Pinephone does not have the extensive GSM and CDMA band support of my old unlocked and rooted Moto G4+ Android spy phone.
When I first moved here 3-1/2 years ago I was a Verizon prepaid service subscriber on the unlocked Moto G4. I found that the service and hardware combination worked on the Inland Cellular towers at my new home via an unusual routing of calls that requires a user to redial a number once a connection is established to an Inland robot. (Inland is a small regional provider and not an MVNO.) The roaming system is the result of an agreement between Inland and Verizon.
Pre-paid Verizon accounts could be setup with reserve funds on deposit, which Verizon applied to any Inland roaming surcharges. Post-paid Verizon accounts received roaming on Inland for free. I think it's the same Verizon/Inland deal today. Verizon coverage maps often do not distinguish between the Verizon tower areas and the Inland tower areas that provide the roaming service. My recent experiences have confirmed that this roaming agreement and system is still in place.
3-1/2 years ago, an AT&T SIM card received no signals here at home. Pinephone doesn't work with CDMA but, after buying my Pinephone and knowing that AT&T has expaned its network, I tried new SIM cards in my Pinephone:
My H2O (an AT&T MVNO) card has never produced a signal at my home until a few months ago when my Pinephone suddenly received AT&T tower signal with one or two bars of 4G LTE annunciated strength. Despite what appeared to be a usable signal, all H2O calls near my home (and also in other areas away from large towns and cities) are dropped the instant the phone application attempts to place a call. SMS messages don't go out either; they are queued until I drive to a city. Strangely, these problems are with ~50% signal strength being reported!
Shortly after my Pinephone began to pick up these unusable rural 4G LTE signals from the AT&T network, I began to suspect that AT&T had rolled out new B17 equipment in our area. B17 is absent from the Pinephone wiki specification but I read somewhere that B12, which is on the Pinephone's list, is a superset of B17. Apparently the superset B12 is not enough to provide B17 compatibility, which is not a surprise to me.
I continue to suspect that, while the Pinephone is able to detect and report B17 signals, it is unable to use B17. Thus, B17 signal strength commonly displayed and reported via annunciation at the top of the screen or various modem utilities, can be most confusing and misleading to users (at least in my rural area). I also found that my pay-as-you-go H2O account was deducted for all instantly dropped phone calls so there's some sort of account communication occurring over B17 that impacts accounting.
Next I tried an Inland Cellular SIM card, because all the towers around here are Inland towers. Like Verizon, Inland is CDMA so voice only works with VoLTE. Unfortunately, VoLTE isn't yet supported by Inland. Inland 4G data worked great though.
Based on US Mobile reports here in the Pine64 forum, I ordered a free US Mobile SIM kit a week ago (coupon code FREEKIT), which contains their "Super LTE" SIM card (black card/Verizon system) and a second "GSM LTE" SIM card (white card/T-Moblie system). When the card arrived yesterday, I found that the US Mobile activation webpage would not even permit me to activate the white T-Mobile card using my zip code. (It reported that service is unavailable in my zip code).
I suspected that the US Mobile black SIM card (Verizon network) would connect to nearby Inland non-VoLTE towers instead of Verizon towers, which don't exist here, but I decided to first activate my black card in a Moto E4 phone and try it with my PinePhone anyway.
As expected, the US Mobile black SIM card activated and my outbound calls were routed to an Inland tower, automated bot and a the bot's message told me that I needed to buy an Inland PIN account in order to roam on the Inland system. So much for the US Mobile service area maps (like all cell provider maps)!
Finally and as expected, installing the black SIM card into my Pinephone resulted in no signal or service, because the Pinephone doesn't support CDMA and Inland doesn't support VoLTE. Unlike the CDMA compatible Moto E4, the Pinephone couldn't connect to Inland and access the Inland roaming service bot to pay the roaming surcharge.
Finally, wishing to try US Mobile MVNO's white T-Mobile SIM card, I started a chat session online with US Mobile. US Mobile customer support confirmed that the white SIM card was not recommended for my zip code but admitted that entering a different zip code into the online activation page would permit me to activate a second line. Regardless of the result of my two paid SIM activations, the US Mobile 14-day free trial policy would apply and one or both of my account charges would be refunded, upon request.
Once again using my Moto E4 for activation, I activated another US Mobile phone number on my account, this time for the white T-Mobile system SIM card, and then installed it into my Pinephone. It works! As with my H2O/AT&T SIM card, US Mobile white SIM 4G LTE signal strength runs about 50% but it's on a band that's Pinephone-usable!
I still need to do more testing but voice calls work, SMS works, Internet data works. I'm
'n US Mobile right now. 
