I don't know anything about 3Com but I saw the topic.

Is it possible to change the voicemail passwords to 8 digit instead of maybe 4 that they may be breaking?

Can your carrier block those calls as the hackers are getting out of the 3Com switch?

Would someone like Adtran have a router that would prevent those calls?

Again, not a 3Com person, just throwing out grasping at straws ideas.

THE Bracha, old blond specialist in Rube Goldberg solutions.