Thread: Caller ID

Caller ID or Calling Line Identification (CLI) data is sent forward from the originating exchange to the terminating exchange in the normal course of setting up a telephone call. It may or may not be forwarded to the called party depending on the originating or sometimes terminating callers line category. eg. it is not forwarded for calls from payphones or from silent (non listed) lines. For some customers ie. emergency services it is always forwarded regardless of the originating customers line category. Hope this makes some sense. The only way something apart from the forwarded CLI info being displayed at the receiving end would be if the CLI info was intercepted at the terminating customer end and some other info was substituted. This is exactly what happens with mobiles when they show the calling persons name on the screen. This substitution is done in the receiving persons phone.
Its been a couple of years since I've worked in this area but I would be very suprised if this has changed.

Deano

Cheers for that, Deano

It sort of confirms my suspicions, but I am thinking that if the CLI can be modified at the originating end, the the flow thru to the receiving end would remain the same.

By my thinking, the CLI that shows a number is only text, picked up in the exchange based on the line used. If we have 10 outgoing lines, then they should be able to all be tagged with the same CLI at the exchange end.

All I want to do, is change the CLI from a number to a word.

I even have Telstra scratching their heads. They say it should be able to be done, but they just aren't sure how.

Not 100% but I think some of the VOIP services offer this as an option.

We are running VoIP at the moment.

I am just having trouble convincing the phone guys that this is a better idea then sending a random number, or no number at all.

The thing is, we have the ability to send our generic 13x xxx number with any outbound call, but for various reasons, it is not practical to do this. But all I am thinking is, to replace that 13 number with a word.

Originally Posted by Basil135

Cheers for that, Deano

It sort of confirms my suspicions, but I am thinking that if the CLI can be modified at the originating end, the the flow thru to the receiving end would remain the same.

By my thinking, the CLI that shows a number is only text, picked up in the exchange based on the line used. If we have 10 outgoing lines, then they should be able to all be tagged with the same CLI at the exchange end.

All I want to do, is change the CLI from a number to a word.

I even have Telstra scratching their heads. They say it should be able to be done, but they just aren't sure how.

Technically and theoretically it is possible to sustitute different info for the calling party CLI. The problem I think would be an accountability and legal one. All calls made in our telephone system for the last 20 years or so have CLI info forwarded. It is a neccessary part of setting up the call and gives a form of accountability/legitimacy/charging validity for the call and its set up. To interfere with this data exchange would compromise this. As for different lines delivering the same CLI info, leaving the technical issues aside, legal and acountability issues would be enough to make this impossible. Remember there is no such thing as an anonomous call in our telephone network. I laugh/cry when I see crime stoppers and other advertisments that say 'ring anonomously' with info regarding whatever. You've got to be kidding. All calls are identifiable and this is due to CLI. To set up a system that could compromise the veracity of this info would, in my opinion, be technically and legally unthinkable.
However, CLI substitution is used, for example, when a temporary satellite service is provided to replace a faulty landline. The satellite CLI info is replaced with the customers phone number at the satellite 'gateway' into the telephone network. This is so that 000 calls can be identified back to the caller and the appropriate response made if address info cannot be obtained by the 000 operator. This is a legal requirement of the carrier providing the telephony service and is the only instance that I know of where CLI substitution is used.

Deano