"I try to encourage him and be that voice of reason."
I'm sorry to tell you this but YOU can't be his voice of reason. HE must be his own voice of reason...if that makes sense. YOU will literally drive yourself insane trying to be a voice of reason.
I only say this because this is exactly how I felt and exactly what I tried to do with my ex ABF who used meth. It does not work.. not when they are actively using drugs and in my opinion especially METH!
They can't hear you! That was the hardest thing I had to come to terms with. On top of that it was not MY job!
The text messages being ignored and the phone being dead were all the same things that my ex did when he was using.
Take care of YOU and only YOU!