I use Xnet fusion at home, and hardly ever use the landline.
The other night, I got a call on it, and when I answered there was some weird squealing on the line.
When I went down to the room where the Linksys modem is, it was making the same sound.

If I power down the router and then power it back up , the sound is gone, until I try and use the landline, then it's back (and on the phone line too) until I power it off again.

Would this be a screwed internal part of the modem / router?
Internet is still going fine.