I'm the same. In general I can be quite anxious about using the phone; when I am depressed I am utterly fearful of it and I hate it. Whenever my cellphone rings and it's a number I don't recognise, I let them leave a message and then I listen to it a few minutes later. I guess it's so I have time to process whatever information the caller was ringing to give me, and formulate how I will respond.
I have always felt I am waaay better at expressing myself in writing anyway, so in general I prefer to communicate via writing (e.g. email) than by speaking (phone).