Ask HN: How to handle telephony ddos?

[ajhit406]

A friend runs a local business that relies on it's hard telephone lines to take orders.

They have recently been getting ddos-ed with robocalls for 20-30min periods and received an email with a ransom notice asking for BTC payment or that the calls will escalate.

They tried blocking a few of the numbers, but obviously the attackers are rotating lines regularly.

They can't only accept calls from a whitelist of callers as many customers are new.

Can you think of other solutions / services that can help out?

[srehnborg]

Few questions that you may or may not want to answer on here.

Who is their telephony provider? Is this a landline or mobile?

What type of business? Could they afford to shutdown their phone number for a few days if they notified their customers? Could they change the number on their website for a brief period of time(Directing calls to a new number)? All depends on where they get their leads from. Maybe setup a quick IVR to deflect the robo calls? Press 1 for sales, press 2 for support, etc. could filter out the robots?

Unfortunately, anti-spam in telecom is limited, especially if they are spoofing the number and changing them up. A service like nomorobo.com might be helpful, but again, depends on their existing infrastructure.

Happy to help the situation. I've been in telecom on the engineering side and sales side for 10+ years. Email in profile.

[Rjevski]

Forward the calls to a number that can handle many simultaneous channels and set up an IVR on that. The IVR would tie up the malicious calls, while forwarding the legitimate ones through to yet another number (your mobile?).

Also, start planning for the future and don’t depend on a single, antiquated technology to acquire customers. Consider this incident like a wake up call.

[ajhit406]

Are there phone number reputation scores that telco's can leverage? Anti-spam strategies seem pretty limited with telephony.

[phillipseamore]

Block international or out of state calls. Very unlikely that the calls are local.

[staticautomatic]

Why? Most robocalls I get are from numbers that were obviously chosen for their small edit distance from my own phone number.