Are you afraid of the phone? It seems we might be a new generation with a phone phobia. I don't think any official studies have been done, but I know that I don't particularly love using the phone and I've heard many friends and peers say the same.
A comment on the linked post above says that it's not fear but inefficiency that keeps them from using the phone, to which I agree. I often get phone calls where people are asking for documents to be emailed to them and then I have to get their email address (hoping I don't misspell something) and email them back anyway. I would just prefer an email in the first place. I'm also just a person who really likes to get to the point and I think email or text messaging does a nice job of that.
Another reason I prefer email or text is that it's always in my face. I mean, when people call and leave a voicemail, I sometimes delete it and then forget about it. I rarely delete emails or texts so everytime I check those, your name is still sitting there waiting for a response.
So now you know why I don't answer my phone.