Well... there is a way to remove the notification at the app permissions level, but it would most likely also squash any notifications coming from the app that created it... i.e. the Phone. And that's probably not the wisest thing to do.
I agree that it is an annoying one, and one that could have been better served by modifying the phone signal status icon instead. Personally, I hate persistent notifications, especially when they are really 'permanent' and not just for when I have an app running that I plan on closing fairly soon, like PocketCast or Waze.