Read the post below for some background but for the moment AT&T has become very unreliable and offers no ability to make voice calls except with a voip provider. Manually select T-Mobile and you should have better success maintaining a stable connection when a network is available.
If you look at the 2G and 4G LTE network coverage for your route from BC to your current location it will make more sense why your Roaming service has been.....crappy....there is very poor coverage especially in Nebraska.
The US does not have the same kind of coverage that Canada has (world leading) and unlike Canada whose network providers have made great effort to ensure nearly every mile of highway in this country has network connectivity. US coverage is population based. Add in mountainous terrain and you have a recipe for unreliable roaming.
A US Sim card may not solve the issue either depending on the provider and how far down the pecking list the provider of the Sim card/service happens to be? Of course once VoLTE is implemented for pm customers that will help improve voice calling but you will still be reliant on being connected to the 4G LTE network same as a voip provider. If it doesn't exist then nobody around you is connected.
Why AT&T has been so hit and miss we do not know but some customers in some parts of the US have no problem connecting to their 4G LTE network while others cannot even find it? It's YMMV currently. Nearly every other Canadian provider has roaming agreements with AT&T only. Public Mobile gives you two options by having roaming agreements with both AT&T and T-Mobile. In that aspect you could say Public Mobile is industry leading?🤔
