Blue&me does seem to vary in its compatibility seemingly from one car to another. For example my 2011 Punto Evo with Blue&me2 works with my iPhone 6s without any problems (a phone made in 2015) and my wife’s brand new iPhone XR. Other people with exactly the same car, report no compatibility at all with any iPhone, having explored all options and eventually given up.
You iPhone “should” work with blue and me the network should not affect that and neither should the age.
It’s also worth noting that fiat NEVER update software on cars, and so never fix these issues.
Most other manufacturers do regular updates on infotainment systems to keep them compatibily with the latest phones.
The best way to play music on a Blue&Me system is to download it onto a Windows-formatted memory stick in .mp3 format and put the stick in the usb slot. You will then be able to use the steering wheel controls to select and play your music.
Using a phone to select music whilst driving is an extremely bad idea. I don't know what the law is in the USA, but in the UK, it'll get you an automatic six penalty points plus a fine if you are caught by the police; that's more than halfway to losing your licence.
If you are an iPhone user and you have all your music on your iPhone and carry your iPhone on you at all times, then it is a massive pain in the arse to go and create a memory stick with all your playlists and favourites songs neatly ordered into folders and files, when you already have this on your phone.
I don’t want to carry around extra unnecessary stuff and don’t want to leave something in the car that will get damaged with heat or cold, or attract thieves. A usb memory stick is a massive inconvenience.
The law on using your phone in the car applies to hand held electronic communications devices, this means if you don’t physically pick it up and hold it in your hand, you can do what you want with it. For example, if you have you phone in a holder and you can maintain full control of your vehicle then you can text and drive. You can access songs and playlist, use satnav and check the lottery results.
With blue&me you should be able to plug in and access all your music functions from the cars controls. And the phone functions as well, it obviously if this doesn’t work it encourages people to reach for their phone. Most new phones will do most things by barking orders and you don’t have to touch them anyway.