Wasn't sure where to post this but I'll start here.
I notice that whenever my wife calls me on her iPhone 6 on Vodafone to me on my Nexus 5 on Skinny that the voice quality is terrible. Like the original 900Mhz analogue.
Then whenever I had poor calls like that with other callers I would ask them what phone and what network and usually it would be an iPhone on Vodafone.
I get great call quality from landlines and callers on other networks so I don't think it's my phone but I would be interested to hear thoughts from other fellow GZ folks.
What I plan to do is when my wife's Vodafone credit runs out is to move her to Skinny also. That should be better voice wise.