I have had UT on a Nexus 4 since Canonical was doing their thing, I was really looking forward to using Ubuntu but if memory serves me it worked, but with a lot issues and no cell or MMS at the time. I parked it a desk drawer then.
I stumbled upon UBports last fall and got the thing to reflash the image with this newer one. I putzed with it a bit but had not tried to use it as a daily driver.
In January I inserted my AT&T and it would not connect to the network.
I reinserted my sim in my IOS and they had locked my account for using an unsupported device. Seemed pretty brilliant to me.
I have since gotten a Patriot Mobile sim and inserted it and they sent a text saying "We see your phone does not have the correct settings to access the internet or send MMS. Setting will be sent to your handset." And it works.
I have been using it this weekend and all the issues are because it is a tired old dog! It's been sleeping in a desk drawer for three or four years! LOL! I am amazed it works most of the afternoon streaming audio to my BT headset. I found a Oneplus One that according to UBports is better supported. Hope so, I like UT a lot better than IOS or Android.
Hope to contribute here.