Aswath Weblog

How to control robocalling

We all hate these annoying, unsolicited calls. FCC has been trying to alleviate the problem by various means. They introduced “Do not call list”. It even ran a “challenge”, in the spirit of crowdsourcing a solution. And now the bright and smart people of IETF are trying to form a group to address this problem using technology. In the kickoff meeting, Henning Schulzrinne, CTO at FCC is quoted as saying, “Number spoofing is root of (almost) all phone evil”. If this is so, then there is a simple procedural solution and it starts with “me”.

I subscribe to Caller ID feature. I pay for it directly or indirectly. So I expect this information to be verified. My carrier claims it is offering this feature, So it stands to reason that its expected to deliver verified information. But this information is generated by yet another carrier and this second carrier has no incentive to deliver a verified information. So the crux of the proposal is to incentivize the upstream chain of carriers.

I suggest that my carrier identify its confidence in the caller id in a three point scale: “verified”, “unverified, but can be challenged”, “unverified and can not be challenged”. The idea is if I answer a call from the second group and conclude that the number was spoofed, I challenge my carrier which propagates upstream. If it is concluded that number was indeed spoofed, a financial payoff follows the reverse path. Since termination charges follows this path, this is not an additional burden. It is recognized that this challenge is resource intensive. So to control my trigger happy nature, I am given a limited number of free challenges, just like we do in sporting events.

There are some potential gotchas. Current Caller ID spec has a way to signify two groups. It is not clear whether the spec can be extended to carry the third group as well. It is not clear how many caller ID devices can display the group. Initiating the challenge process is not difficult. This is just a variation on “last call return”.

I suspect that under this scheme, most of the evil spoofers will not be agreeable to this form of challenge. So those calls will belong to the third group, which I will not answer. But well intentioned spoofers will be agreeable to challenges and over a period of time, the public will gain confidence in this characterization and the number of challenges will decline.