Good question marthaslack!
If someone blocks their number using *67(10-digit number) and calls you, our network will pick it up and still block the call. However, if they use a spoofing program or app (altering their outbound number), our system will not be able to block the call.
I hope that answers your question. Feel free to test it out using a friend's phone to see exactly what the experience is on the calling end.
Follow us on Twitter @VZWSupport