Telstra (Australia). My Nexus 6P experience has been dreadful. Telstra say the phone is not supported on their network so it's my fault for buying one (Telstra are the largest carrier in Australia and, essentially, the only one with reasonable rural coverage - I travel rural for work a few times a year so it's Telstra or carrier pigeons). I've been pretty annoyed at how badly the phone has worked at that level but part of me is willing to accept that Telstra just couldn't care about what is essentially a niche phone. What I've been far more annoyed about is that even though it's a Nexus - I am still beholden to my carrier for (regular, easy, OTA) updates. Google advertised the Nexus as being like an iPhone, where you just get updates from the vendor - but in reality it's no different to a Samsung. You need the vendor to release updates, the carrier to test, etc.