Blocking spam calls

Simon Woodhead

Simon Woodhead

19th May 2022

By Simon Woodhead

TLDR: If your calls to the USA are rejected by us, you need to clean up your traffic because we’ve tightened the screws on our controls.

Today I am writing to you to discuss one of the (many) scourges upon the telephony industry – short duration traffic and robo-calls. 

I am sure we have all had a call from a number we don’t recognise and upon hearing that generic, robotic voice, have immediately hung up the phone.

Being consumers as well as network operators, we have a firm distaste for illegitimate calls – be they robo-calls to our personal devices or clogging up our network and costing us all money as an operator. If you look back at prior blog posts and our efforts to support General Condition C6 (most notably blocking invalid CLI) and embracing of STIR/SHAKEN in the US, I believe that our actions synchronise with our words. But we need to go further.

The US’ FCC is clamping down hard on such calls (oh to have a pro-consumer Regulator I hear Simon sighing) not least because the consumer harm from them is estimated at $10bn a year. We’ve been right on the front foot there with STIR/SHAKEN and other initiatives but many operators aren’t and are now no longer able to terminate traffic. As a result there is something of a big squeeze taking place or put it another way: market consolidation. This is leaving the dodgy robo-call type traffic fewer places to hide and there is an absolute tsunami of it seeking a home. The FCC’s intent is that it finds no home.

As per our MSA we have traditionally taken a stance against dialer traffic, as very little of it complies with Ofcom’s or the FCC’s regulations and typically it’s more trouble than it’s worth! We have recently, however, noted an uptick in short duration calls traversing our network from otherwise clean accounts.

As the only (to our knowledge) UK carrier also licensed in multiple States across the USA and one of the reducing number left standing in the USA, one could understand why we might be seeing more of this. Perhaps calls put into Simwood in the UK exit in the US with a coveted STIR/SHAKEN attestation, and bypass spam controls? Sorry to disappoint! Perhaps though some of our customers are offering this traffic a home? It is tempting if you don’t have the financial penalties passed on, you may simply be unaware of its background, or the perpetrators may have got ever more desperate and creative in abusing retail services to get traffic away.

Rather than simply barring offending accounts, effective yesterday we cranked up some of our anti-abuse controls – the same ones that enable us to not pass on dirty origin surcharges to you. As a result, if you’re passing calls to the US and we think, in advance, that one of them is going to be a spam call, we will block it. You’ll see calls rejected to you with an ‘unviable destination’ reason. Of course, if we think the call is legal and legitimate, it’ll pass as normal.

The purpose of this blog is to let you know about this change and make you aware of the reasons why. There is nothing to shout at our support team about, or indeed vent on Community Slack about. The system is fully automated and our team will not override it. This is 100% intentional and our response through any channel will be the same: clean up your traffic.

Naturally, if we can clarify any further please just let us know.

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