NC/Dark isn't about ignoring her. You ignoring her calls is not going to solve your problem. If she needs to communicate with you, there has to be a channel open. So, instead of ignoring, let her know that you prefer to discuss matters via text or email, whatever you prefer. I prefer text unless it's something that needs an email. Assert your boundary and then stick with it.
If you don't like chatting with her when you do pick up, just say something like - I have to go. Text me whatever it is you want to chat about. And then leave. Do it all politely. Avoidance isn't going to get you respect.
