This is my solution on how to fix the call failed error on the IPhone 6 running IOS 9.2.1. The problem appears to be the voice calling through the 3G or LTE antennas.
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Andreas Christodoulou is the creator and editor of Octopus Technology YouTube channel and theoctopustechnology.com website. Andreas is passionate about technology and computers and uses his knowledge to help people solve tech problems. Andreas also loves making product reviews, discussing tech news and playing video games. Please connect with Andreas on social media above.