Do any telcos do egress filtering of caller ID in NZ?

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Aredwood

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#236414 1-Jun-2018 00:39

Due to all of the threads about scam calls, and faked CLID. Is egress filtering a thing? EG does Spark or Vodafone check that the CLID for outgoing calls is actually set to a number that they manage? Meaning that if a scammer were to use a Spark connection, they would be unable to make any phone calls unless they used a valid Spark number for the CLID. Which is turn would make it far easier to trace the source of the scam calls.

Sure, every Telco in NZ would need to do this. But it would make it a lot harder for the scammers. Withheld CLIDs should be changed to default numbers that would still identify the originating Telco. Incoming international calls can be checked to make sure an overseas number is used. And international Withheld CLIDs could be changed to a default international CLID. So blocking unwanted international calls would be easier.

I'm not picking on Spark or Vodafone in particular. Just using them as example.

I get that there will be setup costs. But the results would be worth it.

Aredwood

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#2026609 1-Jun-2018 01:16

Even better would be if CLID could be verified against the account used to make the outgoing call. And withheld CLIDs could be set to a standard prefix with the remaining numbers randomized. But the Telco recording which random number was used for each call. So the calls can still be traced back to an account if needed by the Telco. But still provide privacy to people who want to hide their CLID.

SaltyNZ

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#2026634 1-Jun-2018 06:59

Aredwood: Even better would be if CLID could be verified against the account used to make the outgoing call. And withheld CLIDs could be set to a standard prefix with the remaining numbers randomized. But the Telco recording which random number was used for each call. So the calls can still be traced back to an account if needed by the Telco. But still provide privacy to people who want to hide their CLID.

In the signalling, CLI withheld is a simple flag. The CLI is still there, it's just not presented to the terminal.

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sbiddle

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#2026637 1-Jun-2018 07:13

The simple answer to that is yes - probably 99% of PRI and VoIP users will have no ability to set their CID to anything other than their number.

While some of the numbers are spoofed via wholesale connections that do allow setting of CID (and I'm not going to name any providers in here because I don't think it's a simple name and shame situation), some are genuine and are spammers that are simply signing up and then abusing a service before being disconnected. They then just sign up again with a new number.

Aredwood

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#2027332 2-Jun-2018 01:04

Interesting. I was thinking partly in terms of the fake Chinease Consulate scam calls. Where people were reporting that the CLID was set as the actual phone number of the consulate.

Does that therefore mean that those scam calls had to of originated in NZ. Or at least from a NZ based wholesale account (linking over a VPN to somewhere overseas).