Craigslist and VoIP Spam Prevention?

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Written by Brian Scott, COO and Labs

The internet needs a free, universal registry of telephone numbers. That’s sort of tangentially related to ENUM (Telephone Number Mapping), but I would guess that legacy telecom is too snooty to cooperate with any sort of movement like that.

It would be wonderful if, after receiving a nuisance call, or identifying a fraudster/phisher, I could look up the company that provides service for that phone number, perhaps with an abuse contact that I might actually have a conversation with.

I see a lot of parallels between abuse of phone numbers and abuse of IP address space. IP Address space is done this way today – if you identify a spammer or hacker, you can always contact the company who “owns” the IP by checking with ARIN [American Registry for Internet Numbers].

The availability of this information allowed free DNS-based blacklists to spring up, which are now one of the pillars on which SpamAssassin and the like are built on today. Of course, nothing’s perfect, but it’s something.

Sure, resources like exist, and while they are great for some uses, they aren’t really usable in this situation, once you consider resellers, LNP, and the like. If I did take the time to locate the correct company I would probably end up wasting 30 minutes in a menu, and wasting some more time talking to a call center agent who won’t help me. With the right equipment and money, I can gain access to legacy telecom’s SS7 network, but even that won’t get me down to the reseller level.

I’m not suggesting that a registry provide information to associate a phone number all the way down to the end-user. Sure, we need to maintain some semblance of privacy. But why shouldn’t a list that associates phone numbers down to the company responsible for the service (and the company capable of terminating service) be public domain?

Take Craigslist, who (allegedly) recently started refusing to provide service to certain VOIP users who happen to be using telephone numbers from the Level(3) Communications network. If a free, universal ENUM registry existed on the internet today, Craigslist could be less heavy handed — in the spirit of the spam whitelists and blacklists out there today, Craigslist could simply record abusers and stop providing service to phone numbers on those networks.

With a nice use case, DNS-based blacklists would then pop up, maintained by people who hated telephone number abuse as much as they hated spam.

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