Who I have the same questioned this topic

My friend is unable to call me. She and i are able to text just fine and i can call her, but when she calls me she says she only gets my voice mail but i receive no notification of a call coming in or that there was a voice mail left. She is in my contacts. She is able to call plenty of other people in our area. I have had a few other occasions when my phone doesn’t ring, but with her it is consistent. Now she has to text me and asks me to call her if she needs to speak to me.  I have rebooted my phone a couple of times. I am able to receive incoming calls from many other people. She is not blocked. I simply don’t know what else to try. Any suggestions?