I used to work at two (UK) telcos. There's a historic reason and a modern reason.

The historic reason was, just like the Internet, the international phone network was built on gentlemen agreements by engineers who largely trusted each other.

A big national telco is unlikely to attack its peers, so there was little need for safety measures. As smaller telcos came in to the mix via deregulation, that understanding changed - but it was hard to retroactively fit controls.

The more modern reason is outsourced call centres. You want outbound calls from your Philippines based staff to show as if they were calling from a local number. When large and reputable entities were doing this it was fine. Just like showing a different reply-to address on an email.

If you were designing a modern network, it wouldn't be like this. But international telephony is over a hundred years old and has a huge amount of legacy technology and legal agreements.

> You want outbound calls from your Philippines based staff to show as if they were calling from a local number.

The company that has offshored it's support to the Philippines might want that, but I doubt any consumers want that. That shouldn't have happened, but regulation comes (20+ years?) after harmful business profit decisions have been made and implemented.

But, thank you for the explanation. I have heard similar explanations before, and it has always sounded to me like a situation where the telcos are able to offer a service for a profit for the customers to hide the origin of their offshore call centres (that mostly nobody wants to speak to anyway).

I think I just ranted twice, sorry. Thank you!

Just looking at my incoming call list on my phone for yesterday: "Suspected Spam", "Suspected Spam", "Suspected Spam", "Potential Fraud", "Suspected Spam", "Suspected Spam", a real call, "Suspected Spam", "Suspected Spam"...

Phone is set to only notify me for numbers for known contacts - does mean that I occasionally miss calls from other people, but I can live with that.

> The more modern reason is outsourced call centres. You want outbound calls from your Philippines based staff to show as if they were calling from a local number. When large and reputable entities were doing this it was fine. Just like showing a different reply-to address on an email.

For this particular case, do they really spoof the caller ID on an (expensive) international phone call, or do they actually just re-route via a local phone number?

> You want outbound calls from your Philippines based staff to show as if they were calling from a local number.

This is a valid use case, but I’m a bit surprised that the mechanism isn’t better controlled. Surely a better design would be for an actual local entity to forward the call, possibly with an optimization to allow the voice data to bypass the local entity once the call is connected.

It's been a while since I did telecoms related stuff but also you might want a different CLI and ANI for forwarded calls so you can preserve the original line being used.

Obviously the whole scam call centre has changed how it has to work but we actually had a working system that had quite a few useful features.

> You want outbound calls from your Philippines based staff to show as if they were calling from a local number

I personally don't? Why would I want that.

The companies might want to hide that info but I don't think that's a legitimate use case.

It's a solved problem. VoIP plus leased trunk lines by the a telco in the market you want to work at. You are limited to fixed set of numbers and you are "local" in the market you want to work at.

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