certifried_scambaits I can't get around their dynamic IVR to play sounds on this one, but I usually can. Not sure why the voice recognition is having issues. However, this is a toll-free number and I am connecting to the IVR system, which costs them. I suspect I am costing them a lot right now, because they don't know I'm connecting :)
I'd be interested to know how you got the voice recognition working, if you don't mind discussing it on the forum. I've got a call flooder that can do that trick, much to SmartFares' chagrin. I wrote it Python using the python bindings for the PJSIP library to talk to an Asterisk PBX box. It gives you much better control over what happens during the call than a bog standard Asterisk call flooder script. The plan is at some point to start building so AI features into it, but laziness on my part is kind of getting in the way at the moment.
I think some scammers might be getting wise to the fact that there are call flooders out there that can use voice recognition now. I've seen some that use tricks like using different recorded voices to read different parts of the message, or ones that give you vanishingly short times to respond to the IVR system.
These particular ones give a very short sample for the speech recognition to work with. If you hit them with enough lines though, you can still get through. :)