Someone's annoying sick idea of prank calling me to death?

Recently, I've been getting a lot of withhelding calls on my landline, whenever I pick up, say "hello" or whatever, there's no sound, about a 2s pause, then the person hangs up.

This happens on a weekend at least 4 times, one day I got it as often as once every 10 minutes.

I'm 99% sure this is a person pranking because:

1.) On xmas there was no blank call spam, but immediately on the 2nd Jan onwards it started again. Additionally, the caller usually calls me around 4pm+ until 8-9pm, which seems to be someone's off-time.

2.) About a week before they started, someone, also calling from a withheld number, called me, asking me I knew who someone called "Steve" was, he was very cryptic and creepy and seemed to think I was joking around when I said I had no clue who he was, at the end of the call they simply tutt-ed and hung up.

That was around 2-3 months ago, and now the spam is neverending to the point where I don't say anything when I pick up a call and wait for someone to say something first.

I've not contacted my telephone provider to see if I can cancel out withheld calls yet, and my phone is pretty out of date (no screen to show the caller). What can I do because its really ****ing annoying.

Suggestion: Get caller ID

EDIT: Apologies, you say 'withheld'
Alternative suggestion: Ignore withheld calls for a few days

Get caller id?

1471

Contact telephone provider.

If to no avail, get a new phone.

Get a new number, if possible. If it persists, contact the police. But call 101 (non-emergency number)

Hi, the number is withheld and so I cannot find his number with 1471, I hear that asking the telephone provider to cancel out withheld calls adds a service charge? I really don't want to spend money to let this troll i broke under pressure if I could.

Is it against the law to do spam calls (how would I contact the police about it?)

@1st reply: the person sometimes doesn't call for days, and one time the family was away from home several days and we found around 20-30 missed calls. the person started calling once a day and once I started picking up, it came more regular again.