Easy, call via some voip implementation or another i often have internet access when i dont have phone service, not rarely have service without internet and therefore voip is already more relible. Moreover, its also quite clear who is calling me, so spoofing isn't viable. cellular based calls are dead and belong buried.
Not all would, but most worthwhile clients support end to end encryption, or some form of authentication which is time consuming to circumvent, meaning it becomes quite difficult to efficiently spoof random identities.
