Does anyone know how to enable contacts that once worked but now do not?

[AC Question]

I have two particular contacts on my phone that are people that I have known for years. All of a sudden, I cannot text them or call. My calls go straight to voicemail and texts do not go through. I was getting texts from one, but my texts didn't go back and now nothing at all. I only know all of this because I have contacted them via email. Any idea how to fix it? Called my carrier and they have no idea.

 

[B. Diddy]

Welcome to Android Central! Did you ask them if they accidentally blocked you as a contact?