Calls can be blocked on Sprint.  You can block inbound and outbound calls for up to 50 phones numbers. Enter each 10 digit phone number below or quickly add numbers you've previously blocked by accessing your archive list (archive list numbers will be saved for 90 days). Archive list - showing the most recent 100 entries.

Here's a how: Sign into account, go to my preferences > Limits and Permission > Block Voice > click on radial dial for "Block only the following phone numbers for inbound and outbound calls" > enter phone number to be blocked