PinePhone Carrier Support
This page contains hints on setting up cellular network connectivity for specific carriers. For more general information, see Modem and carrier support. For the APN settings see PinePhone APN Settings.
Carriers
T-Mobile
According to this page, T-Mobile's primary frequency band for the United States is 12 (700ac MHz).
T-Mobile's bands and protocols are summarized on this page.
While the Pinephone's modem does support all LTE bands that T-Mobile uses in the US (And is one of the best choices for band support with the Pinephone's modem in the US), VoLTE is still listed as "Under development" by the modem manufacturer. T-Mobile's system also does not list the Pinephone as a compatible device due to this lack of official VoLTE support. The modem is capable of working on T-Mobile with VoLTE support enabled "unofficially" however. (It's also very possible that the manufacturer of the modem will eventually add "official" support)
Cricket Wireless
Cricket wireless is a MVNO that uses AT&T's network. VoLTE is fully supported and the pinephone is considered a compatible device in the US by the carrier.
Verizon
According to this page, Verizon's primary frequency band for the United States is 13 (700 MHz).
Verizon's bands and protocols are summarized on this page. However, it also says:
This carrier only accepts approved devices on its network. Even if a device supports some or all of the required frequencies for this carrier, it will not be able to connect unless the device is approved for this network. Check with the network operator to confirm whether a device is approved or not.
According to a "Verizon Agent" on a chat session:
We are the network operator and we will check whether the device will be compatible. For that, we need to have the device's ID (IMEI number). This will be on the device's purchase box; the device ID can also be found under device settings.
Issues
The FrequencyCheck model page does not list either Pine64 or the PinePhone.
Tmobile's system does not list the pinephone as a compatible device due to the lack of official VoLTE support from the manufacturer, despite the fact that it does work.