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Old 29-03-2019, 12:46 PM   #5539
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Join Date: Dec 2001
Posts: 34,581

In short caller ID is a service one subscribe to enable your own display name to appear on the persons phone you called.

By default without caller ID only the phone number will show.

Our local telecos stretched the definition of caller ID by blocking the display of phone numbers as well as the display name when you do not subscribe to caller ID.

Only having a custom display name requires the telco to have its own database.
Just displaying of phone numbers does not require any special effort on the telco part. Probably why MVNOs can afford to give "caller ID" for free as it does not require any additional work on their part.
the thing is... your "ID" i.e. the phone number that u are familiar with... is not necessarily the actual phone number tied to your telco/account...

problem comes when IDA (now IMDA) mandates number portability for all telcos... hence to do this... telcos implement number portability via the "display name" thing...

but underlying when u sign up a new telco and ask to port your number... what happens is u get a "dummy number" (this is the real number that is allocated to that telco) assigned to u first... which is why when u get the SIM card from the telco and try to use it immediately to call someone... u see a different number (i.e. the dummy number) until number porting takes effect... and the telcos have to store this ported number somewhere... and hence the display name is used to store this ported number since we don't actually use that to store name here... unless you are some organization which is why sometimes the caller ID shows alphanumeric name rather than only numbers...

hence the caller ID service that telcos need to implement is to figure out your "display name" which happens to be the phone number that carries along with you whenever you port your number... without this Caller ID service... either the phone number you see will get will be the "wrong" number... or you won't be allowed to do number port in the first place...


Last edited by wackykid; 29-03-2019 at 12:56 PM..
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