It was not 600. And there is no one that will absolutely guarantee that a device will or will not blow up the MTA.
In fact, if your existing phones could blow up the MTA, why did you plug those in.
Most of us will plug it in and be done. There is no real concern here unless we create one.
I want to send a fax using an HP all-in-one machine. I was thinking of just plugging it directly into the wall as if it's just another phone. My concern is that I want to make sure I don't damage the expensive voice modem that I rent from Comcast. I think it costs something like $600 to replace. I also use a cable modem from Comcast. So can I just plug the fax into a phone port on the wall and try it?
I'm also curious as to how Comcast's expensive voice modem works. Does it just convert outgoing phone calls from analog signals on the copper lines to digital signals traveling out of the house on the coaxial line? So it would treat an outgoing fax in the same manner?