Does Norton's ask to be called by phone?

A popup said I should phone an 0800 number (from UK) when I tr4ied to download something.  It said there was a Trojan, it was dangerous to try to remove it myself as it would wreck the hard disk, and it looked Norton-ish, including having the name Symantec and  colours etc.  From curiosity I phoned the number and got music, I listened for about 20 seconds.  Am I to assume this was a trick designed to get me to call and expensive number?  Does Norton's ever really ask people to call a number?  Of course I should also ask whether in fact the message was genuine and I have a problem?

Johnbee