Caller ID

Random

At which point is the caller ID on someones number?

For example, if I restrict my phone number and ring my mate. Does the caller ID get blocked when it gets to the O2 switchboard, or does it get blocked when it reaches his networks switchboard, or does it get blocked when it gets to his phone?

Now, I know O2 can see my number when I ring their customer care (for example), even on private number ... so that rules out my phone/sim as the block anyway.

spank_inferno

ciaranfo wrote:

At which point is the caller ID on someones number?

For example, if I restrict my phone number and ring my mate. Does the caller ID get blocked when it gets to the O2 switchboard, or does it get blocked when it reaches his networks switchboard, or does it get blocked when it gets to his phone?

Now, I know O2 can see my number when I ring their customer care (for example), even on private number ... so that rules out my phone/sim as the block anyway.

I think it gets blocked when the call is forwarded by the recipient network to the destination number.
Your network will see your number otherwise they cant bill you.
The recipient network will see the number so they know who to bill the call termination charge to aswell. (though mabey I'm wrong on this?)

Random

I would have imagined that the recievers phone would need to see the number too in order to link both phones together for the call?

Which is why I wonder if it's at a phone level?

rogue-entity

IIRC, its Automatic Number Identification, when you call someone, the exchange logs the callers line number, this is irrespective of CallerID which is a service to allow residential customers to easily ID callers numbers when it isnt blocked. ANI was developed for billing purposes. In the US, anyone who owns an 800 number will automatically receive the numbers of all callers regardless to CallerID. I assume it is the same for our 1800 numbers.

ns06

You can block your number either on the handset (yourself) or by the network (via the helpdesk), therefore it's being blocked either way.

Remember, your number is only what you use to ring from and for people to ring, it's not what gets picked up by the network when you make a call. That would be your IMSI.

Your IMSI connects to the HLR, and the HLR holds all your subscriber info on what you can do eg. voice calls, sms, international calls and caller ID etc

For more info check out this site which explains it in more detail

http://www.shoshin.uwaterloo.ca/~jscouria/GSM/gsmreport.html

JohnnieM

The IMSI (International Mobile Subscriber Identity) is a unique 15-digit code used to identify an individual user on a GSM network.

The IMSI consists of three components:

* Mobile Country Code (MCC)
* Mobile Network Code (MNC)
* Mobile Subscriber Identity Number (MSIN)

The IMSI is stored in the Subscriber Identity Module (SIM).

To answer the question..the networks withold the number for you..if you choose to withold it..(they can still see who you are)