Another method that works, regardless of phone: Verizon offers a Call-Block service via their Customer Service. I think you're allowed to block up to 6 numbers.
Dial 611, then press 3 (Tech Help) and ask the CSR to set up a call-block list on your account. Give her any numbers you've saved (domestic 10-digit only) and there may be a time limit (not sure). You can call later to add or delete numbers on your list. You may have the option to do this online too; ask the CSRep. Works on all Verizon residential/wireless accounts.
I've got a different Android phone, but over the past few months since buying the app below I've found it to be a great $6 investment to block calls from unknown numbers, or repeated solicitation calls: Extreme Call Blocker
First, set up a contact for the caller as a name such as "SPAMMER1" or be more descriptive. Second, go into the contact edit section under "SPAMMER1" and change their received call area to "send to voicemail"
now all their calls go directly to voicemail and you don't have to even hear them calling.