I don't think you understand what I was saying. I have a t-mobile phone, but I use metropcs sim and service.
I have tested both metropcs and t-mobile modems. on both stock roms and this 7.1.2 rom. all modems give me volte on stock rom, but on this 7.1.2 rom the volte and 4g lte will disconnect as soon as a phone call is made, or an incoming phone call is coming in. As soon as this happens it turns into H+ or 3g for the duration of the call.
After the call is over it will return to volte 4g. So basically volte is just an icon and doesnt actually work. Yet on the stock rom volte works fine I can recieve calls and make outgoing calls using volte with no problems, and it doesnt drop my internet connection. like lets say I am streaming a youtube video on 7.1.2 the video will stop or if I am using wifi tether my computer will not have internet during call, and will have to reconnect once call is over because it switched from 4glte to h+ or 3g. I am wondering if anyone actually uses the volte 4g on the 7.1.2 and how they got it to work because it is just for show as far as I can tell for me.