When a phone number is blocked, it means that the recipient of the call has chosen to not receive calls from that number. There are a few ways to get around this block, but they all involve using a third-party service or app.
One way to call a blocked number is to use a Virtual Private Network (VPN). A VPN encrypts your internet traffic and routes it through a server in another location. This makes it appear as though you are calling from a different number, and the call will not be blocked.