What's missing here is a good ol' conspiracy theory.
For years I have used Samsung, the last 2 were Galaxys, the last an otherwise brilliant GT-S5839i, until I got a landline call from a great nephew asking why I hadn't replied to his texts about my car repairs. I never received them ... I visited him and checked his mobile, he definitely had everything correct. Then my daughter who is in touch with me every day and is also on the 3 network said she had phoned and texted several times without me replying. After inquiries I was told my old Samsung was not suitable for 4G and 3G was prone to dropouts due to the impending changeover.
So I bought a German / Chinese ZTE super smart phone, at least it's smarter than me, and everything worked fine for a week or so ... then my daughter rang the landline ( it's getting removed very soon anyway ) and said I hadn't returned her texts. So it's not the phone, it's the 3 Network, their town centre mast is masked by tree growth and probably the wrong kind of leaves on the rail lines.
Unfortunately the ZTE can't distinguish Text Message Incoming Tones from Facebook, Gmail, Amazon and his dog so I made it worse by choosing a very pleasant birdsong which might be a bit silly as the songbirds are out in force in my garden, so I now just ignore the phone and have issued orders to those who wish to communicate with me to Ring / Call when they send a text but don't wait for an answer .. but at least I'll know I've had a text message.
The ZTE has an interesting feature, to answer the phone I merely have to lift it to my ear. I'm puzzled as to how a phone can recognise my ear, until I remember the Facial recognition and Reconstruction Software in use everywhere and that completes my theory ...
AI (Artificial Intelligence) is out to get us - in fact - it has got us.
watch what you say - somebody is listening, and recording, just ask Boris
cheers, Ian