Rang me on my iPhone, when I answered, hung up.

keeps calling me but is disconnected when i try and call back.

Calls at least 15 times a day even though the number is blocked, so annoying, this number needs to be traced and these people arrested arrrgh

This is called CALLER ID SPOOFING.

Definition according to the US Federal Communications Commission (FCC)...

Caller ID Spoofing is '...an "escalating numerical assault" by an out-of-state (or country) telemarketer or, more likely, a criminal debt collector trying to swindle you out of money you don't owe'

Caller ID Spoofing allows the user to send out a false phone number for your caller ID service to register that is not really the originating number. When you call the number it's usually a disconnected number, so that when you call back you don't get a real person; you get the "that number has been disconnected" recording. With escalating numerical assaults, the crook's computer dials every local area code and every prefix and then 0001, 0002, etc. - until every number in a region has been called.

This number is still calling constantly even though i have blocked it.

Caller: compare energy or something like that

Called me a number of times yesterday and today, answered the phone today, and apparently it's a energy comparison company wanting to help me compare energy companies. Never requested anything at all like that so I just said I wasn't interested and said goodbye. Annoying!

Harrassing nuisance number - block it or blacklist it - if it's ringing you it's smarter to ignore the number incase the automated machine knows youre a human and continues to target you.

counted 15 calls but number was blocked, pest scammer

silent call hangs up, rang back says number cant be connected to

Caller: Dodgy

Calls all the time despite blocking the number

This number must be checking to see if your number is connected as by some of the comments here

Keeps calling me when i answer they hang up and when I call back there numbers disconnected...

Hung up as soon as I answered,

What the hell that number I don’t understand

Caller: Caller hangs

I agree with all these comments... Annoying caller

This number calls me many times a day. I turned on call silencing. The caller never left a message. From what I read it strongly indicates it's either a scammer or one those energy comparison calls where they have to get their "prospect" on the phone in order for them to profit from a sale.

Caller: compare energy

Blocked but still call my phone every 20 minutes - just in case I answer

Compare energy...!

This number keeps ringing even though I have blocked it, either I pick it up and it hangs up and when I call back it says number disconnected on a dodgy line or I get the better deals or electricity comparison

Compare Energy cold call. If you don't request changing your utility provider, hang up.