I had wifi calling with At&t using my S5 phone and with the new S9+, there was no way to use wifi calling so it can't be carrier specific as both Samsung and both on At&t.
If you want all your features working you must flash the carriers firmware and have there bloatware on your phone, flashing the unlocked firmware wont work on at&t.. I use my Samsung factory unlocked note9 on metro by tmobile and everything works, when I had it on cricket volte and wifi calling would not work, the carrier only allows these features on iPhones, all my call were dropping to h+ and I dont get h+ inside my house so I missed all my calls, after about a year of this I switched both of my phones to metropcs and have everything working and my speeds are 3 times as fast, wifi calling is nice, but volte is even better, all my calls connect almost instantly and sound great.. u can download the carriers firmware from sammobile.com..
All newer phones from like the s7 and up will work on all carriers and have both cdma and GSM bands.. at&t only accepts at&t branded phone with all features, not sure about Verizon.. tmobile is the least picky about this from my experience.. just search this topic about your phone theres lots of information on reddit, some phones can be tricked by swapping simcard from iphones, iphones get provisioned with all features working then swap the card back to the Samsung, I've read this works but might fail after a few days..
If you want all your features working you must flash the carriers firmware and have there bloatware on your phone, flashing the unlocked firmware wont work on at&t.. I use my Samsung factory unlocked note9 on metro by tmobile and everything works, when I had it on cricket volte and wifi calling would not work, the carrier only allows these features on iPhones, all my call were dropping to h+ and I dont get h+ inside my house so I missed all my calls, after about a year of this I switched both of my phones to metropcs and have everything working and my speeds are 3 times as fast, wifi calling is nice, but volte is even better, all my calls connect almost instantly and sound great.. u can download the carriers firmware from sammobile.com..
All newer phones from like the s7 and up will work on all carriers and have both cdma and GSM bands.. at&t only accepts at&t branded phone with all features, not sure about Verizon.. tmobile is the least picky about this from my experience.. just search this topic about your phone theres lots of information on reddit, some phones can be tricked by swapping simcard from iphones, iphones get provisioned with all features working then swap the card back to the Samsung, I've read this works but might fail after a few days..
I actually bought the unlocked Verizon note 9 512gb 8gb ram version. I can tell you that it's got both the GSM and CDMA radios and capabilities in the device. My carrier is AT&T. So popped my AT&T into the phone and right away it restarted and loaded the AT&T firmware. Interesting thing was I was still on Android 9 firmware. I know for a fact that the all note 9s received the Android 10 firmware update because I have another AT&T branded note 9. So I called the the store UbreakIfix and asked them if they could push Android 10 onto my phone. They told me absolutely they could with no charge. So yesterday I go there and got Android 10 put on my note 9 and all the services work. Wifi calling, video calling, volte all work. The interesting thing is in the phone settings *#*#4636#*#* it shows wifi calling, video calling, volte greyed out. However I've tested all those services and they're all working on my unlocked Verizon note 9 on AT&T.
Yes it's ridiculous. Verizon is the same way. T-Mobile is different. Which show is that it's not a problem with Samsung software. IPhones do work unlocked with Wi-Fi calling for some reason maybe Apple has more clout. They make a step forward allowing unlock and then they disable great new features like Wi-Fi calling for unlocked phones
I have the same problem and have been working with ATT/FirstNET for months to try and resolve this issue. They keep saying it is a Samsung problem. Wifi calling is on the phone and installed, but will not work. Furthermore, the phone does not display 4gLte either which is another problem with unlocked phones. I get LTE only and H or H+ with slow speeds, but my work phone, ATT also "not unlocked" gets 4glte while I ger H+ whatever the heck that is. I figured if you go "unlocked" every feature should be available no matter what carrier. I wanted the unlocked phone so i dont have the bloatware and can change providers at will. It has been more of a headache than it is worth with an unlocked phone.
I suggest switching to metropcs or tmobile, or mint mobile and save some money and get everything working.. although it does require you to have a phone that has all the bands that are required to get the best performance on any network.. my note9 has like 36 bands and will work on all networks, only problem I had was on at&t trying to get wifi calling and volte, everything works flawlessly on metro by tmobile and I get consistent 150mbps download and 50mbps upload any time of day at my house.. tmobile network has grown very fast and is still growing.. it was the worst in my area a few years back, I just switched a month ago and had 3 bars everywhere, today I get full bars and LTE+ almost everywhere I go, I predict in the next 10 months tmobile will have just as good of coverage as Verizon
