How do i block NO CALLER ID calls on iPhone 6

Lots of customer are facing the annoying calls from unknown callers (can be spammers, telemarketers etc.)  They usually do not reveal their caller ID  and you will see an incomeing call with “No Caller ID” on screen. You may want to block but won’t be able to do it easily as you cannot possible identify the number of a caller before answering or putting directly them to Reject list in your iphone. These calls are also known as Anonymous, Private, or Blocked in some parts of the world. Since it is not easy to block this calls so requires a little work from your side.
5 ways to block no caller id call

Below are some quick tips or fixes to block unknown caller Id on iphone.

Solution 1: User external apps.
There is an app/website which offers the service like you forward your unknown calls or without caller id to them and they will forward the call back to you with the real number. It works for them because because they have a toll free number which gives them more billing information about the number calling.

Solution 2: Use voicemail to block unkown caller Id calls
You can start doing is for calls that don't allow for caller ID, allow them to go over to voicemail.  Actually huge number of those calls with no caller ID will refuse to leave a message on voicemail as they will be interesting in calling me that they can't leave a voicemail, so you don’t have to worry about calling them back either. It should certainly cut down on the number of phone calls you have to deal with using voicemail as a filter.

Solution 3: Use DND to block unknown calls
First you should block all numbers not in your contacts list.
This will include everyone with no Caller ID announcement.
Now go to->Settings->Do Not Disturb->Manual->Allow Calls From->All Contacts
Quite simple! Now only persons in your contacts list will be able to make a call to you.

Solution 4 : Take help from your Carrier service provider
Pick up the next three unknown calls to understand who they are from, whether they are automated marketing calls, and whether they are all related.
If it is a person mistakenly dialing you or crank calling you - unfortunately not much can be done.
If it is an automated marketing call from the same company over and over - your carrier should be able to block them from calling your number. Call them.

Solution 5: Using Contacts
·         Create a new contact, you may name this new contact “No Caller ID”. Here is how:
·         Launch the Phone app ->Tap Contacts->tap the + button
·         In place of phone number, enter 000-000-0000->Tap Done

·         Now scroll down and tap Block this caller. A popup will appear saying “you will not receive phone calls, messages or FaceTime from people on the block list” then tap Block Contact.

Hope you might get helped by this.